A wind turbine generator set cabin outside meteorological sensor fixing device comprises a vertically fixed hollow supporting rod. An interface for mounting a meteorological sensor is formed in the top end of the supporting rod, the bottom end of the supporting rod is connected with a base sucker through a ball-and-socket joint, a plurality of pull rings are arranged on the upper portion of the supporting rod, the upper ends of pull wires are fixed into the pull rings, the lower ends of the pull wires are connected with pull wire suckers, the base sucker and the pull wire suckers are adsorbedon the outer surface of a cabin by the aid of atmospheric pressure, and the base sucker provides supporting force and lateral slip prevention friction force for the supporting rod. The invention further provides a fixing method using the device. The device is simple in structure, light in weight, convenient to carry, mount and detach and particularly applicable to performance testing of a large wind turbine generator set, punching and welding operation on the cabin is omitted, the sensor can be fixed without destructively transforming the cabin of the wind turbine generator set, damage to a cabin anticorrosion coating and sealing performance is avoided, and set performance testing is facilitated.