The paper introduced the design of a portable cotton moisture meter with BP nerve net(NN) of 2-6-1 topology for non linear correction of water and temperature compensation and the device adopted the RC/F and AIFCS technologies to improve the capacity of resisting disturbance to the signal. The meter was tested and the results showed that the measure error was less than ±0.4%（moisture 5%-15%) or ±0.5%(moisture 15%-25%) when the temperature was -20-50 ℃. The device avoided the influence of temperature variety to moisture, increased the anti-jamming capacity of measure signal and satisfied the actual requirements of cotton moisture measure.