Relay intercropping of legumes with cereals is a useful technique for yield increment. Intercropping may affect the photosynthetic pigments, enzyme activity and yield of barley and chickpea under water stress. To investigate the effect of relay intercropping of barley with chickpea on pigment content, enzyme activity and yield under water stress, a field experiment was conducted during 2017 and 2018. The treatments included irrigation regimes (normal irrigation and cutting off irrigation at the milk development stage) as the main plot. Also, cropping systems as sub plot consisted of sole and relay intercropping of barley with chickpea in two sowing dates (December vs January). Under water stress, the early establishment of barley in December intercropped with chickpea in January (b1c2) enhanced the leaf chlorophyll content by 16% compared to sole cropping due to less competition with chickpea. Late sowing of chickpea enhanced the leaf carotenoid content of chickpea, catalase and peroxidase activities. Barley-chickpea intercropping enhanced the WUE and guaranteed a more efficient use of space (land equivalent ratio of more than 1) compared with sole crops. Under water stress, in b1c2enhancement of total chlorophyll and water use efficiency caused to increase the grain yield of barley. In b1c2,barley and chickpea reacted to water stress with increasing total chlorophyll and enzyme activity, respectively. In this relay intercropping treatment, each crop occupied and used the growth resources from different ecological niches at different times, which is recommended in semi-arid areas.