The invention discloses a multi-arm folate receptor targeted medicine conjugate modified by water-soluble polymer, and salt thereof. The medicine conjugate has the following structural formula as shown in description. The invention is a multi-arm polymer modified targeted anti-cancer conjugate; the water-soluble polymer modification can enhance the water solubility of the conjugate, thereby improving drug loading capacity. The targeting molecule is folic acid, the folic acid is served as the targeting molecule and actively targeted to the tumor cell rich in folate receptor expression, the anti-tumor effect can be well played, the targeting is increased, and the concentration of the conjugate in a target tissue is higher.