The present invention discloses a constant-temperature rotation device. The device can drive a copper cavity body to rotate via an actuator, and then control the temperature of the copper cavity body and capture the fluorescent signal from each test tube in the copper cavity body during the rotation of the copper cavity body. Since the rotation of the copper cavity body will cause the wires of the thin-film heater twisted, thus, the constant-temperature rotation device further provides two copper bars and the corresponding tracks in order to solve the winding problem via slide-contact. Moreover, the constant-temperature rotation device adopts single light channel, including single stimulating light source and single light detector respectively located at the upper side and lateral sides of the copper cavity body, which can effectively make the signals of multiple test tubes become more consistent.