Deformation potential theory was employed to estimate relaxation time of Ba2ZnPn2. Seebeck coefficient of Ba2ZnAs2 monotonously increases with increasing temperature. p-type Ba2ZnAs2 shows a potentially higher thermoelectric performance than Ca5Al2Sb6. The peak ZT value along z-direction for p-type Ba2ZnAs2 is larger than 2. The chain-like structure may induce a high electrical conductivity along z.