In this study predication of crop coefficient (Kc) values through growing season for cucumber plant was conducted. A field experiment was carried out at AL Yusufiyah Township, in the Governorate of Baghdad, (latitude: 33°09' N, longitude: 44°24' E, and altitude: 34 m) in medium loam soil. The plant was cultivated inside the greenhouse under subsurface trickle irrigation system with soil water retention technology (SWRT) during the growing season 2017. Crop coefficient values were guessed from the direct method of measurements of daily crop evapotranspiration, while reference evapotranspiration was obtained from Agricultural Meteorology Project - Station of Baghdad - Abu-Ghraib.  The obtained results were showed that crop coefficient values for initial, mid and late of season growing stages were: 0.1, 1.29, and 0.9, respectively. Comparison with other local work was showed similar values of Kc. Although the type of irrigation and utilizing new techniques of saving the applied water which reduced the ETc value by about 132 % comparing with other, the reference evapotranspiration value was plays an effecting role in calculating the Kc values.