Unmanned technology changes human lifestyle. The high-precision map with the lane line attribute plays a crucial role in the unmanned field. Proposing a detection method based on MultiRes + UNet network, aiming at the problem that the low accuracy and low efficiency of existing algorithms in the detection of composite lane lines. This method expands the convolution receptive field by dilated convolution to co-ordinate global information. The MultiRes block and Res path structure are used to reduce the difference between the encoder and decoder features, which greatly reduces the memory requirement. The experimental results show that the proposed algorithm improves the detection speed of the algorithm while ensuring the detection accuracy. When the pure lane, compound lane and shadow fouling lanes are obtained, the harmonic mean F1 scores are 0. 959, 0. 942, and 0. 891, the algorithm is high efficiency and high robustness.