According to the especial requirement for optical coating in fiber communication passive devices, complicated wavelength division multiplexing(WDM) filter coating was demanded on optical fiber pigtail, in view of the difficulty about the coating deposition on optical fiber pigtail, an initial quarter film was given by resolution method by using TFCalc formula design software, then gradient optimization method was combined to partly optimize the initial formula, and the layer sensitivity of the formula was analysed by combining deposition equipment to assess the robustness and the deposition feasibility, then the formula of wavelength division multiplexing(WDM) filter coating on optical fiber pigtail was obtained with good spectral properties. The internal structure and deposition technology of LEYBOLD APS1104 deposition machine made in Germany was improved to deposit the designed formula by using ion assistant deposition with low temperature, the wavelength division multiplexing filter coating on the optical fiber pigtail with good performance was acquired.