The invention discloses an elevator well anti-falling partition system and a construction method. The construction method comprises the following construction steps: (1), performing construction preparation; (2), pre-burying side wall square steel in a wall; (3), mounting a shaped placing corbel; (4), mounting a hard shaped partition main beam; (5), mounting partition frame fixing secondary beams,and stretching secondary beams on the two sides; (6), placing a partition plate and mounting a shaped guardrail; (7), erecting a safety protection net; (8), splicing a shaped platform plate; (9), welding and mounting an internal obliquely-supported hard partition frame; (10), welding and mounting an internal obliquely-supported hard partition frame; (11), splicing a shaped protective door; (12),mounting a shaped fixing clamp; (13), mounting a shaped protective door; (14), mounting a shaped main beam mounting and detaching limiting frame; (15), removing the shaped partition frame main beam; (16), detaching the protective door. According to the construction method, the danger of elevator well construction can be effectively reduced and huge social benefits are generated.