Abstract: In this study, a non-corrosive carbon fiber reinforced polymer (CFRP) grid is arranged in thick concrete cover to solve the problem of wide crack opening and poor durability of reinforced concrete components under service conditions in hydraulic structures. We conduct experimental tests on totally 12 simply supported thick-cover reinforced concrete beams under four-point monotonic loading ? 9 with CFRP grid and 3 without, and analyze influencing factors of crack spacing and width, such as concrete cover thickness and the size and number of CFRP grids. And we derive a formula for calculating crack width using the existing theory of concrete cracking and the models of concrete crack width. Results show that CFRP grids effectively control crack propagation in thick-cover reinforced beams. And either an increase in CFRP grid number or a decrease in CFRP grid size can increase cracking load and reduce the maximum crack width and average crack spacing. Calculations of the maximum crack width are in good agreement with test measurements, and thus our crack width formula helps the design of CFRP grid reinforced concrete covers.