Effect of hydraulic sand fracturing depends on flow conductivity of fracture to some extent. Influenced by formation lithology，proppant type and closure pressure，flow conductivity of the fractures dropped quickly in tight carbonate reservoirs，which may has an impact on recovery percent of reserves. How to choose the proppant to improve fracture flow conductivity at high closure pressure is very important. The evaluation experiment of flow conductivity of propped fracture by hydraulic sand fracturing in the tight carbonate rocks was carried out with various types of proppants using multi-function testing and analysis system for flow conductivity of the fractures. The results show that with the increase of the closure pressure，the drop rate of fracture flow conductivity using 16/30 mesh medium-tenacity ceramsite proppant is significantly higher than that using 20/40 mesh medium-tenacity ceramsite proppant；when the closure pressure exceeds 69 MPa，the flow conductivities were similar for both proppants；however，the flow conductivities of fractures are quite different from each other if using high-tenacity ceramsite proppants having the same size with the former two. The flow conductivity of multisized high-tenacity ceramsite proppant is similar to that of 16/30 mesh high-tenacity ceramsite proppant，but the breakage rate of single-sized proppant is larger，which cause more formation damage. Under high closure pressure，the flow conductivity of several kinds of multi-sized proppant was tested，and the best was selected as 16/30 mesh（60%）+20/40 mesh（20%）+30/50 mesh（20%）.