The invention mainly relates to an agricultural machinery, in particular to a structure of an alfalfa seeding machine. A small hard seed stepless precision drill comprises a rack consisting of a suspension device and a load bearing platform; a sowing depth regulating device and a traveling ground wheel transmission system are arranged below the suspension device; a seed metering device and a fertilizer feeding device are arranged above the load bearing platform; and an opener and an earth covering and pressing device are arranged below the load bearing platform. The small hard seed stepless precision drill is mainly characterized in that helical transition slots are arranged on seed metering wheels of the seed metering device; a single chain wheel is arranged on a ground wheel shaft of the traveling ground wheel transmission system; a drive chain is connected with a duplex chain wheel arranged on a fertilizer feeding shaft by the single chain wheel; and a second drive chain is connected with a triple chain wheel arranged on a seed metering shaft by the duplex chain wheel. The small hard seed stepless precision drill has novel design and compact structure, is simple and convenient to operate and has strong universality and good complete machine adaptability. Particularly, by the matching and regulation of the helical transition slots on the surfaces of the seed metering wheels and the duplex and triple chain wheels on the fertilizer feeding shaft and the seed metering shaft, the stepless precision seeding of small hard seeds can be implemented, the seeding quality and the working efficiency are improved, the yield of the agriculture and the grassland farming is ensured and the crop or grass mechanical harvesting working conditions are improved.