Objective To develop a novel synergism compound suspension concentrate of niclosamide and chlorphoxim (Co-SCN) and sdudy its characteristics. Methods Niclosamide and chlorphoxim were milled by a ball mill and mixed with different amounts of wetting agent. disper-sant agent, thickener, and water etc. , to develop Co-SCN, and the pH value, thickener, grain size were evaluated. The ultraviolet absorption spectrum of niclosamide and chlorphoxim were measured. The content of niclosamide and chlorphoxim in the solution were assayed by HPLC. Results Co-SCN was a gray thickener fluidity liquid. It was very easy to disperse and could be mixed with water in any proportion. Its pH was 8. 65 and thickener was 137 mpa? s. The grain sizes (diameter) were from 0. 138-19. 953 ?m. Of them more than 95. 6% was smaller than 10 ?m and more than 82. 24% was smaller than 5 ?m. There were three peaks of ultraviolet absorption spectrum for niclosamide: 210, 234 nm and 334 nm respectively. One peak of chlorphoxim was at 269 nm. The novel formulation contained 20.64% niclosamide and 5.26% chlorphoxim. The suspension stability of Co-SCN was 100% for 2 hours and 89. 14% for 4 hours, and otherwise WPN in water was speedy sediment. Conclusion The novel synergism compound suspension concentrate of niclosamide and chlorphoxim is a stable quality and standard formulation.