The utility model relates to a slide rail type telescopic loading platform of an electric tricycle, which comprises a back plate and a first loading plate, the back plate is fixedly mounted on the front portion of a loading plate base, side plates are mounted on two sides of the loading plate base through rotating shafts, a semi-through groove is formed in the upper portion of the loading plate base, and a guide supporting slide rod is mounted on the center line of the semi-through groove through a support. The two sides of the second cargo carrying plate are installed in the cargo carrying plate base semi-through grooves through sliding rails, sliding blocks are fixedly installed on the lower surface of the side, facing the back plate, of the second cargo carrying plate, and the sliding blocks are movably installed on guide supporting sliding rods. Two or three grooves are formed in the rear portion of the cargo carrying plate base to install the telescopic supporting beams, and the supporting blocks are arranged at the ends of the telescopic supporting beams. According to the telescopic cargo carrying platform, a conventional cargo bucket is improved to be the cargo carrying plate base, the second telescopic cargo carrying plate is installed, the length of the cargo carrying platform can be increased, and the telescopic cargo carrying platform can effectively adapt to long farm tools, bamboo poles, water pipes and the like.