In response to issues such as high transmission loss, poor amplitude-phase consistency, and weak anti-interference capability in traditional millimeter-wave direction-finding technologies, a high-precision millimeter-wave direction-finding technique based on microwave photonics is proposed. This technology integrates parallel Mach-Zehnder modulator（MZM）coherent photonic frequency conversion with multi-baseline interferometric direction finding algorithms, achieving low-loss transmission and high-fidelity frequency conversion of millimeter-wave signals through optical-domain signal processing. A multi-channel array antenna pattern calibration method is employed to compensate for system amplitude-phase errors, while an approximate interacting multiple model（IMM）direction finding filtering algorithm is utilized to eliminate abnormal direction finding values. Simulations and experimental results demonstrate that this technology reduces the direction finding fluctuation range from 27.2°~32.5° to 29.7°~30.2°, with a maximum mean square error of 0.31°, significantly outperforming conventional microwave direction finding methods.