This paper introduces the importance of two-color infrared detectors for target identification, explains the operating principles of common two-color infrared detectors, and points out the limitations of spectral crosstalk test methods. Integrating the crucial role of response voltage in practical applications, the response-voltage crosstalk test method is demonstrated based on the principle of Planck blackbody radiation. Calculation results show that the spectral crosstalk from the long-wave band to the mid-wave band for the example two-layer two-color detector is 13.7%, while the response-voltage crosstalk from the long-wave band to the mid-wave band is 2.3%. Imaging verification shows that the crosstalk ratio from the long-wave band to the mid-wave band in actual application scenarios is approximately 2.4%, demonstrating the practicality of the response-voltage crosstalk test method. This method is applicable not only to two-layer two-color infrared detectors but also to single-layer spliced two-color infrared detectors, providing valuable insights into the development of two-color infrared detector chips.