In order to establish precision model, a software to calculate the strip crown of four-high hot rolling mill was developedby using affecting function method according to the strip crown calculation theory. The effect of work roll diameter,unit width rolling load, roll bending force, work roll crown, initial strip crown and reduction, etc, on load distributioneffect rate was simulated by using the software. The results show that the load distribution effect rate increaseswith the increase of strip width, work roll diameter, unit width rolling load, roll bending force, work roll crown,initial strip crown and reduction. Based on the simulation results, base value of load distribution effect rate andfitting coefficients of six power polynomial of load distribution effect rate modification coefficient were determinedconsidering all of the above parameters. A simplified mathematical model for calculating load distribution effect ratewas established. In order to establish precision model, a software to calculate the strip crown of four-high hot rolling mill was developed by using influence function method according to the strip crown calculation theory. The effect of work roll diameter, unit width rolling load, roll bending force work roll crown, initial strip crown and reduction, etc, on load distributioneffect rate was simulated by using the software. The results show that the load distribution effect rate increases with the increase of strip width, work roll diameter, unit width rolling load, roll Based on the simulation results, base value of load distribution effect rate and fitting coefficient of six power polynomial of load distribution effect rate modification coefficient were determined by all of the above parameters. A simplified mathematical model model for calculating load distribution effect ratewas established.