Abstract: The temperature and transformation coupling calculation model of FEM was established for hot rolled strip of Q345 steel in 3mm thickness at run out table during laminar cooling.Then the temperature,phase transition and residual stress distribution in width of hot rolled strip during laminar cooling was calculated.The difference of temperature,transformation and residual stress in width of strip by two kinds of laminar cooling process was analyzed.The results show that the temperature and phase volume fraction in width of strip tended to be uniform after laminar cooling with crown profile water flow.The residual compressive stress in the edge of strip was reduced by 80 MPa and the maximum strain difference of the strip in width direction after cooling decreased from 7.69×10^-6 in conventional even profile water flow laminar cooling process to 3.71×10^-6.It was favorable for the hot rolled strip having better flatness.