diff --git a/docs/en/modules/gpio.md b/docs/en/modules/gpio.md
new file mode 100644
index 00000000..b3fd098f
--- /dev/null
+++ b/docs/en/modules/gpio.md
@@ -0,0 +1,127 @@
+# gpio Module
+
+This module provides access to the GPIO (General Purpose I/O) subsystem.
+
+All access is based on the I/O index number on the NodeMCU dev kits, not the internal gpio pin. For example, the D0 pin on the dev kit is mapped to the internal GPIO pin 16.
+
+If not using a NodeMCU dev kit, please refer to the below GPIO pin maps for the index<->gpio mapping.
+
+| IO index | ESP8266 pin | IO index | ESP8266 pin |
+|---------:|:------------|---------:|:------------|
+|    0 [*] | GPIO16      |        7 | GPIO13      |
+|        1 | GPIO5       |        8 | GPIO15      |
+|        2 | GPIO4       |        9 | GPIO3       |
+|        3 | GPIO0       |       10 | GPIO1       |
+|        4 | GPIO2       |       11 | GPIO9       |
+|        5 | GPIO14      |       12 | GPIO10      |
+|        6 | GPIO12      |          |             |
+
+** [*] D0(GPIO16) can only be used as gpio read/write. No interrupt support. No pwm/i2c/ow support. **
+
+
+## gpio.mode()
+
+Initialize pin to GPIO mode, set the pin in/out direction, and optional internal pullup.
+
+####Syntax
+`gpio.mode(pin, mode [, pullup])`
+
+####Parameters
+  - `pin`: pin to configure, IO index
+  - `mode`: one of gpio.OUTPUT or gpio.INPUT, or gpio.INT(interrupt mode)
+  - `pullup`: gpio.PULLUP or gpio.FLOAT; The default is gpio.FLOAT.
+
+####Returns
+`nil`
+
+####Example
+```lua
+gpio.mode(0, gpio.OUTPUT)
+```
+####See also
+  - `gpio.read()`
+  - `gpio.write()`
+___
+## gpio.read()
+
+Read digital GPIO pin value.
+
+####Syntax
+`gpio.read(pin)`
+
+####Parameters
+  - `pin`: pin to read, IO index
+
+####Returns
+number:0 - low, 1 - high
+
+####Example
+```lua
+-- read value of gpio 0.
+gpio.read(0)
+```
+####See also
+  - `gpio.mode()`
+___
+## gpio.write ()
+
+Set digital GPIO pin value.
+
+####Syntax
+`gpio.write(pin, level)`
+
+####Parameters
+  - `pin`: pin to write, IO index
+  - `level`: `gpio.HIGH` or `gpio.LOW`
+
+####Returns
+`nil`
+
+####Example
+```lua
+-- set pin index 1 to GPIO mode, and set the pin to high.
+pin=1
+gpio.mode(pin, gpio.OUTPUT)
+gpio.write(pin, gpio.HIGH)
+```
+####See also
+  - `gpio.mode()`
+  - `gpio.read()`
+___
+## gpio.trig()
+
+Establish a callback function to run on interrupt for a pin.
+
+There is currently no support for unregistering the callback.
+
+####Syntax
+`gpio.trig(pin, type [, function(level)])`
+
+####Parameters
+  - `pin`: **1~12**, IO index, pin D0 does not support interrupt.
+  - `type`: "up", "down", "both", "low", "high", which represent rising edge, falling edge, both edge, low level, high level trig mode correspondingly.
+  - `function(level)`: callback function when triggered. The gpio level is the param. Use previous callback function if undefined here.
+
+####Returns
+`nil`
+
+####Example
+
+```lua
+-- use pin 1 as the input pulse width counter
+pin = 1
+pulse1 = 0
+du = 0
+gpio.mode(pin,gpio.INT)
+function pin1cb(level)
+  du = tmr.now() - pulse1
+  print(du)
+  pulse1 = tmr.now()
+  if level == gpio.HIGH then gpio.trig(pin, "down") else gpio.trig(pin, "up") end
+end
+gpio.trig(pin, "down", pin1cb)
+
+```
+####See also
+  - `gpio.mode()`
+___
diff --git a/mkdocs.yml b/mkdocs.yml
index 5cc23e0b..0e248048 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -31,6 +31,7 @@ pages:
     - Modules:
         - 'adc': 'en/modules/adc.md'
         - 'crypto': 'en/modules/crypto.md'
+        - 'gpio': 'en/modules/gpio.md'
         - 'node': 'en/modules/node.md'
         - 'file': 'en/modules/file.md'
         - 'rtcmem': 'en/modules/rtcmem.md'