The high-speed railway rail-laying vehicles is large-scale special vehicles, its automatic drive can improve precision and efficiency for laying rail. This paper presents rail-laying vehicle framework and automatic driving function, designs automatic drive control system based on CAN-bus. Especially, hydraulic steer model is set up by analyzing the steer system of rail-laying vehicles, resolves the bottleneck problem of automatic steering during vehicles automatic drive by studying rail-laying vehicles' guiding method and fuzzy adapting PID control strategy of automatic steering. Simulation experiment proves this method is effective.