Based on the panel data of 108 cities in the Yangtze River Economic Belt from 2003 to 2019, the functional radiation range of the four major central cities in the Yangtze River Economic Belt is investigated. Its found that under the influence of producer services, the relationship between urban productivity and the distance to above cities presents a cubic “∽” curve, that is, with the distance getting further, the productivity has experienced the process of decline, rise and decline, but there are also great differences. Specifically, Shanghai radiation capacity can cover the whole Yangtze River Economic Belt in the whole time period and Chongqing began in 2005. Wuhan and Chengdu show a cubic “∽” curve relationship within their urban agglomerations respectively. The regression based on distance found that the radiation capacity led by producer services exceeded the radiation range measured only by distance, and the spatial distance was greatly compressed.