Due to the great diversity in protein expression productivity, a customized transient gene expression (TGE) method was used in the present study to optimize transient expression of three antibodies. Several factors, including host cells, temperature, valproic acid (VPA) treatment, various vectors, and additives were optimized independently and then combined to form a customized TGE protocol for each antibody. In the event, the optimized TGE conditions for three antibodies were different from each other. Compared with the TGE in CHO-S cells by pCDNA3.1 expression vector, the expression productivities of 8C11 cAb, 37 hAb, and 10F7 cAb showed 16-fold, 293-fold, and 19-fold increases respectively by the customized TGE method. For 8C11 cAb, coexpressing L-chain and H-chain on different plasmids led to higher yields. The customized TGE method is an alternative approach that can greatly improve the expression productivity of a variety of recombinant proteins.