The invention relates to the field of 
linearity testing, and discloses a testing method for automatically testing 
linearity, which comprises the following steps: Step 1, setting a basic 
linearity testing interval, and carrying out local division; step 2, setting a step 
diameter range of an 
optical power test; 3, the 
light attenuation value is adjusted, so that the light power reaches the target light power generated by the test; step 4, adjusting the 
light attenuation value to enable the light power to reach the target light power to be tested, and repeating for five times; and Step 5, if the difference between the five times of 
light attenuation and the power value is smaller than the target value, the average value of the five times is used as the actual light attenuation and power value, and a 
responsivity linear test calibration calculation basis is generated. By adding a scheme capable of automatically testing the product linearity, the method is high in testing efficiency, can well adapt to 
mass production, is low in production cost, can provide convenient calibration measures, is convenient for a user to complete 
automatic testing by 
programming light attenuation and light power, can verify the testing accuracy, and guarantees the qualified rate of finished products.