Abstract: Based on the basic principles of digital city management and ray tracing algorithm，a new method was put forward that can model systemically and simulate numerically field intensity of electromagnetic radiation around the mobile communication base station of city communities by using the steps of threedimensional entity environmental modeling， reverse ray tracing path searching and the field intensity synthesis computing of radiation source multiple ways of spreading in order.This method can effectively overcome the limitations that traditional wave propagation prediction model can not adapt to the complicated construction model in different residential environment and other deterministic methods can not accurately find the radio propagation path.In different spatial distribution areas of city community，the good consistency of computer software simulation results of this algorithm and field measurement results verified that the method is practical，effective and correct.