The invention provides a low-power consumption low-flow resistance smoke temperature gas composite fire detector. The detector comprises photoelectric smoke sensing parts (A and B), a CO sensor (C), a temperature sensor (D), an air outlet hole (E) with an optical labyrinth, a streamline detection cavity (zeta), a filtering net (I) with an optical labyrinth, a communication chip (F), a circuit board (H), an alarm horn (J), an indicating lamp (K) and a shell (G). According to the detector, due to the adoption of the streamline fire detection cavity, a fluid pressure loss coefficient zeta of the inner wall of the cavity is controlled to be about 0.006, so that the smoke flows smoothly in the detection cavity; due to the adoption of the streamline detection cavity, the response speed of a conventional detector is at least improved by four times; and moreover, due to the adoption of a method for combining a low-power-consumption element and a control algorithm, the power consumption of the whole detector is controlled to be about 50mW.