The influences of continuous extrusion plate sizes on the microstructure and properties of C19210 alloy were investigated, and the extruded plates with three sizes were prepared by continuously extruding the cast rod. Then, the three extruded plates were rough rolled, aged and finished rolled, respectively, the microstructure of extruded and rolled plate was observed by metallographic microscope and transmission electron microscope, and its mechanical properties and electrical conductivity were tested by using universal tensile machine, hardness tester and eddy current conductivity meter. The experimental results show that the larger the sizes of extrusion plate, the more deformation heat is generated during the continuous extrusion process, and the better the solution effect, which promotes the precipitation of the smaller second phase particles during aging, so that the prepared finished product has smaller grain size, higher mechanical properties and softening resistance property. Compared with the finished product prepared by the small-size extruded plate, the tensile strength of the finished product prepared by the large-size extruded plate increases from 404.1 MPa to 414.6 MPa, and the anti-softening hardness increases from 98.7 HV to 102.3 HV.