The objective with this research was to calibrate and validate the AquaCrop model for the forage cactus cultivar Opuntia stricta (Haw.) Haw, in order to simulate crop yield and make the model applicable to the simulation of yield in the semiarid region. The AquaCrop model version 5.0 has four modules, which cover aspects related to climate, crop, irrigation and soil and, these modules were fed with the data collected in an experiment carried out at the Experimental Farm of the National Institute of the Semiarid (INSA), located in the municipality of Campina Grande city, PB, in the mesoregion of Agreste, Brazil. Based on these data, yield estimation was carried out, observing the effect of water on crop yield. To validate the model, the data obtained in the field at the irrigation frequencies of 7 and 28 days were compared with the results estimated by the AquaCrop model. The calibration and validation of the AquaCrop model for the forage cactus cultivar Opuntia stricta (Haw.) Haw, presented satisfactory results for the simulated productivity when compared to the yield obtained in the field for the irrigation frequencies of 7 and 28 days, making AquaCrop a model applicable to the simulation of yield and responses to water stress of these crops, which can assist the producer in the decision-making process on his property.