The invention relates to a novel soft rope strut type hanger for a box girder. Two ends of two primary brace rods are connected to form a rectangular frame through two secondary brace rods; two end parts of the primary brace rods are connected with lower connecting pieces which are connected with one end of each primary cable-stayed sling; the other end of each primary cable-stayed sling is connected with upper connecting pieces which are connected by secondary horizontal inhaul cables; and two upper connecting pieces on one side of the end part of each primary brace rod are connected with equalizing beams and then are hung on a main hook of a crane ship, while the two connecting pieces on the other side are respectively and directly hung on the main hook of the crane ship. The novel softrope strut type hanger has the advantages of light weight, simple structure, short manufacturing period, reduction of the problem of load transfer caused by four asynchronous hooks, small wind-engaging area, reduction of external loads, small volume, convenient detection, storage and transportation, high selection of safety factors, capability of being applied to the hoisting of other concrete box girders in different sizes only through little change, high use reliability, little stress concentration and low manufacturing cost.