The invention discloses an agricultural water retention agent which comprises the following components according to parts by weight: 70-100 parts of acrylic acid, 30-40 parts of sodium hydroxide, 18-30 parts of acrylamide, 10-22 parts of starch, 5-15 parts of polyvinyl alcohol, 0.15-0.5 part of cross linker, 10-20 parts of clay, 6-15 parts of fiber, 0.5-2.5 part of evocating agent, 2-6 parts of alkane and surface active agent and 3-8 parts of rest components. The invention also discloses a production process of the agricultural water retention agent. The water absorbing coefficient of the agricultural water retention agent reaches 3000 times and the water absorption of 0.5min reaches 1500 times. The invention has good saline and alkaline resisting performance and long service life, integrates the advantages of two sorts of super water absorbent of a starch graft system and a synthetic polymerization system and can be biodegraded, and matters after treating are organic nutrient substances which can be absorbed by plants. The invention has simple protection process, low cost and stable performance and can be widely applied to the technical field of the water saving and moisture preservation, and the like of agricultural and forestry soils in dry lands.