Disclosed herein are methods for preparing non-dripping flame retarding masterbatches and filamentous non-dripping flame retarding materials. First, an admixture including a flame retardant, a crosslinking agent, a thermoplastic polymer, and a dispersing agent is prepared, and then a crosslinking initiator is added into the admixture to form a composition which is then compounded and pelletized to obtain the non-dripping flame retarding masterbatch. The resultant non-dripping flame retarding masterbatch is suitable for use in a spinning process to obtain filamentous non-dripping flame retarding materials.