Low-frequency excitation magnetic field coils are potent tools for studying the effects of magnetic fields on cells. However, the existing excitation magnetic field coils are vulnerable to external magnetic fields and difficult to generate a high uniform excitation magnetic field with a small size. Thus, this study proposes a novel optimization design method combining the target field method (TFM), thickness mirror image method, and fruit fly optimization algorithm (FOA) to design a new type of biplanar excitation magnetic field coil placed in a near-zero magnetic cell incubator. Based on the optimization design method, three biplanar coils of ${B}_{x}$ , $B_{y}$ , and $B_{z}$ with the paralleled arrangement in a near-zero magnetic cell incubator with the size of $365\times 336\times200$ mm were designed and measured. The coil constants of $B_{x}$ ( $B_{y}$ ) and $B_{z}$ are 8860 and 100 640 nT/A, respectively. The nonuniformity of the $B_{x}$ ( $B_{y}$ ) and ${B}_{z}$ coils is less than 5% and 1% over the central volume of $80\times 80\times80$ and $100\times 100\times100$ mm, respectively, meeting the most requirement of working space and the amplitude of magnetic field for cell research.