Cadmium manganese telluride (CdMnTe) is an excellent room temperature nuclear radiation detector material, which can be used in environmental monitoring and industrial non-destructive testing. A room temperature planar detector with a size of 10 mm×10 mm×2 mm was fabricated using In doped Cd0.9Mn0.1Te crystal grown by Te solvent Bridgman method. The spectroscopy responses of CdMnTe detectors were investigated by irradiation of γ-ray from 241Am@59.5 keV source. By characterizing parameters of infrared transmittance, resistivity and energy spectrum response, the quality, electricity and detector performance of CdMnTe crystal were comprehensively evaluated. The results show that the infrared transmittance of the wafer are above 55%, up to 60%. The leakage current under 100 V bias voltage reduces from 9.48 nA to 7.90 nA after wet passivation. The resistivity after wet passivation is 2.832×1010 Ω·cm. Under the reverse bias of -400 V, the energy resolution of CdMnTe detector for 241Am@59.5 keV γ-ray source before and after passivation is 13.53% and 12.51%, respectively, and the electron mobility lifetime product after passivation is 1.049×10-3 cm2/V. The variation of energy resolution with voltage was studied. When the bias voltage is no more than 400 V, the energy resolution of the detector is mainly determined by the carrier collection efficiency. While when the bias voltage is more than 400 V, the energy resolution is affected by the leakage current of the detector. The research results show that the CdMnTe crystal grown by the Te solvent Bridgman method has good crystal quality, and the resistivity and electron mobility lifetime product can meet the requirements of detector preparation.