Abstract: The aim of the study was to select a suitable pelletisation aid of valsartan immediate-release pellets in the extrusion process and optimized the formulation. The properties of the pellets with five excipients which were microcrystalline cellulose(MCC), low-substituted hydroxypropyl cellulose(L-HPC), crospovidone(PVPP), pregelatinized starch(PCS)and k-carrageenan were evaluated and compared by the single factor test. And the pelletisation aids were chosen preliminary. The properties of the pellets with MCC, L-HPC, k-carrageenan respectively were evaluated and compared and k-carrageenan was determined as the most appropriate pelletisation aid. The Box-Behnken design was employed to optimize the formulation. The optimised formulation was k-carrageenan 16. 98 g, HPMC-E5 2. 03 g, SLS 0. 26 g. The yield and aspect ratio of pellets was 91. 23% and 1. 14, respectively. And there was no significant difference between observed and predictive responses. The results showed k-carrageenan pellets owned properties of a high yield, acceptable sphericity and fast drug release.