The invention provides a design method of continuous casting, rolling and quenching processes. The method is characterized by including: 1), drawing temperature variable curves of a casting-blank surface in the entire process form continuous casting to heat delivering and a casting blank with certain depth, of the casting-blank surface; 2), drawing time temperature transformation TTT curves of undercooled austenite of steel grades in the same graph; 3), adding process feature locations in the same graph; 4), according to the position of intersection points of the temperature variable curves and the TTT curves in the graph, determining the starting position of grain boundary embrittlement of the austenite; 5), according to the starting position, of the grain boundary embrittlement of the austenite, determined in the step 4), determining the position for executing the quenching process. With the method, formation position of a grain boundary banded structure of the scale surface of the casting blank is determined at the design stage according to the steel grades in production and continuous casting and heat delivering processes, and quenching position and capacity of quenching equipment are determined; in actual production, the quenching process is determined according to the steel grades in production and the continuous casting and heat delivering processes.