The invention belongs to the field of flexible mechanisms, and particularly relates to a constant force supporting mechanism based on a flexible Sarrus mechanism. The constant force supporting mechanism is characterized by comprising at least six rigid rods and hinges connected with the at least six rigid rods, wherein the at least six rigid rods are in rigid articulation through the hinges to form a spatial six-rod single-degree-of-freedom mechanism; the at least six rigid rods are namely the first rod piece, the second rod piece, the third rod piece, the fourth rod piece, the fifth rod piece and the sixth rod piece; the second rod piece is connected with the third rod piece through the third crossed spring piece type flexible hinge; the third rod piece is connected with the fourth rod piece through the fourth crossed spring piece type flexible hinge; the fourth rod piece is connected with the fifth rod piece through the fifth crossed spring piece type flexible hinge; and the fifth rod piece is connected with the sixth rod piece through the sixth crossed spring piece type flexible hinge. According to the constant force supporting mechanism based on the flexible Sarrus mechanism, the structure is simple, the carrying is convenient, the stability is good, the reliability is high, and therefore the constant force supporting mechanism is applicable to places and fields in which the output of a constant force is needed, for example, realizing a constant force in fitness equipment and providing an auxiliary body support in medical surgical operation processes.