The invention discloses a method for automatically forming patterns in the design of a power system of a thermal power plant, and belongs to the technical field of thermal power plant engineering design department power system design. The method comprises the following steps of: 1, establishing an interaction interface under a computer aided design (CAD) platform; 2, establishing standard electric equipment blocks; 3, defining the attributes of all the electric equipment blocks; 4, establishing CAD patterns of single devices in a power system deployment diagram; 5, establishing the CAD patterns of the single devices of a power system device list; 6, establishing the CAD patterns of the single devices of a power system terminal board outgoing line; 7, defining the standard format of a power system cable inventory; and 8, generating a finished product. By the method, the technical problems of power supply device missing, writing errors, finished product format non-uniformity and the like in the conventional power system design methods are solved.