Sensitive material of MQ-3 gas sensor is SnO2, which has a lower conductivity in clean air. When the target alcohol gas exists, the sensor’s conductivity is higher along with the gas concentration rising. Please use simple electronic circuit, Convert change of conductivity to the corresponding output signal of gas concentration. The MQ-3 gas sensor has high sensitivity to Alcohol and has good resistance to disturb of gasoline, smoke, and vapor. The sensor could be used to detect alcohol with different concentration, it is with low cost and suitable for different application.