Abstract: Based on the balanced homodyne detection technique of the Kirchhoff's law,a new testing method was proposed. In the related optical communication experiments, light path was often built by complex operation, and required a high degree of the experimental environment, these requirements were omitted in the process of testing. the quantum noise photocurrent signal which was needed in balance homodyne detection could be directly do the amplification test, amplification effect of the weak quantum noise photocurrent signal could be judged. In addition, the high sensitive and high gain were the key to the amplifying circuit of this detection, and the weak quantum noise could be amplified in the test. The test results showed that the amplifiedquantum noise can be tested simply.