The invention provides a preparation method of gallium nano-rods and application thereof in manufacturing a nano-motor. The method includes the steps that materials are put in the proportion that 1 gof liquid metal gallium corresponds to 200 mL of dispersion medium, wherein the dispersion medium is a mixture of deionized water and isopropanol; ultrasonication is conducted for 3-6 h through a probe ultrasonication instrument with the ultrasonic power controlled to be 800-1000 W, wherein during ultrasonication, it is needed to supplement dispersant lost due to ultrasonic cavitation; after ultrasonication is finished, the obtained dispersion system is subjected to standing for 10-14 h to be fully aged; the aged dispersion system is centrifuged for 3 min at 1000*G, and supernatant is taken, wherein the supernatant contains the prepared liquid metal gallium nano-rods; after the liquid metal gallium nano-rods are obtained, controlled aggregation can be conducted in a dispersion system underlocal illumination, and then the photoresponsive micro-nano motor with patterned group behaviors is obtained. The method has the advantages that preparation is fast and convenient; besides, the obtained particles can be used in the photoresponsive micro-nano motor and have good application prospects.