For new copper online cooling equipment, the heat transfer coefficients of impinging jet and flow cooling on the surface of copper plate are obtained through the finite element method. The results provide boundary conditions for temperature field computation. Three-dimensional temperature field compute model is built. Different nozzle horizontal distributions are designed. After calculation, the nozzle arrangement of cooling uniformity is obtained. The jet distribution density curve is used to get the transverse cooling intensity curve. The study provides theoretical basis for obtaining straight plate.