OBJECTIVE： To optimize the formulation and preparation technology of Propylthiouracil （PTU） solid lipid nanoparticles（PTU-SLN）and to evaluate the quality of PLN-SLN. METHODS： PTU-SLN was prepared by emulsion ultrasound dispersing method. The formulation of PTU-SLN was optimized by orthogonal design with the entrapment efficacy and particle size as index， using the amount of lipid material， soybean lecithin and poloxamer 188 and ultrasonic time as factors. The quality of prepared nanoparticles was evaluated with particle size， Zeta potential， entrapment efficiency， stability and in vitro drug release rate as index. RESULTS： The optimal formulation and technology was as follows as lipid material 0.6 g， soybean lecithin 1.0 g， poloxamer 188 0.8 g， ultrasonic time 10 min. The obtained PTU-SLN was round and smooth in appearance and distributed evenly in particle size with average particle size of 93.5 nm， Zeta potential of －30.8 mV and average entrapment efficiency of 74.9％. Prepared nanoparticles had no significant change after placing for 15 d at 4 ℃. Accumulative release rate of PTU-SLN was 56.1％ at 4 hour in vitro and reached 98.4％ at 24 hour. CONCLUSIONS： PTU-SLN is prepared successfully and reasonable in technology， and can reach sustained-release effects.