The invention relates to a spiral grading sieve, which mainly solves the problems of great abrasion, blockage of sieve pores by North China fritillary root, sieve clinging by fritillary soil of high humidity and low sieving efficiency in conventional sieves. The spiral grading sieve is characterized in that a first layer of sieve surface (6) and a second layer of sieve surface (7) have a 'concave' type formed by parallelly arranged threaded rods (8); threaded ribs and grooves on adjacent threaded rods (8) form sieve pores; the end heads of the threaded rods (8) are fixed with gears (9); gears (9) on adjacent threaded rods (8) are meshed with inert gears (10) under the gears; and belt transmission is adopted between one threaded rod (8) inside the first layer of sieve surface (6) and a diesel engine (3), and between the other threaded rod (8) inside the first layer of sieve surface (6) and a threaded rod (8) inside the second layer of sieve surface (7). The spiral grading sieve has the characteristics of less sieve abrasion, difficult blockage of sieve and high sieving efficiency.