A photonics-assisted simultaneous detection method of distances and directions for multiple targets is proposed based on polarization multiplexing and spectrum symmetry. A linear frequency modulation transmitting signal is generated by photonic frequency doubling. The echo signals are received by a three-antenna based linear array. The intermediate antenna supplies overlapped reference spectra by orthogonal modulation. According to specific spectrum symmetry, the de-chirped frequencies of echo signals from each target are clearly distinguished through polarization demultiplexing. Thus, distances and directions can be decoupled for multi-targets without direction ambiguity. Three-target proof-of-concept experiments have verified that the average measurement errors of distance and direction are 3.7 cm and 0.39°. The direction measurement range is up to 166.78°. A multi-target detection scheme with a large direction range is provided for the complex electromagnetic environment.