The invention discloses a glass fiber impregnating agent for reinforced gypsum, which comprises a silane coupling agent, a film forming agent, a lubricant, an antistatic agent, a pH adjusting agent, and water; the contents of the components, by weight, are as follows: (1) the content of the silane coupling agent is 0.10-1.0%; (2) the total content of the film forming agent is 2.5-25.0%, wherein the film forming agent is composed of cross-linking-type and homopolymerization-type PVAc emulsions; (3) the content of the lubricant is 0.04-1.0%; (4) the content of the antistatic agent is 0.02-1.0%; (5) the content of the pH adjusting agent is 0.04-2.0%; (6) the content of water is 88.5-97.5%. Twistless roving for reinforced gypsum produced by using the impregnating agent formula of the invention has the characteristics of good short cut performance, less hair, no electrostatic accumulation, easy dispersion into monofilaments in gypsum, and the like, and can meet requirements for production technology and performance of gypsum composite materials.