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Horizontal continuous casting is a common method to produce copper strip. It is very important to explore the influence of process parameters on the quality of the billet. The influence of drawing speed on temperature field, liquid hole depth and cooling rate in mold was analyzed by numerical simulation, and the influence mechanism of drawing speed on the structure of billet was revealed by process test. The results show that with the continuous increase of the billet drawing speed, the depth of the liquid hole in the mold continues to increase, and the cooling rates of the surface and core of the billet along the traction direction gradually decrease, and the difference between the two cooling rates gradually decreases. When the drawing speed was 149mm/min, the cooling rates of the two parts reach the same. With the continuous increase of the billet drawing speed, the angle θ between the grain growth direction and the traction direction on the section of the billet increases gradually, the grain growth distance was shortened, the number of grains on the surface of the billet increases, and the average grain diameter decreases from 1.96mm to 1.05mm, and the overall microstructure uniformity was obviously improved.