The dissolution rates and bioavailability of norfloxacin in seven batches of norfloxacin capsules produced by five pharmaceutical factories were studied with rotating basket and UV-spectrophotometry. The results showed that the T50, Td and m of the samples had obvious differences, and the correlation between the dissolution rate and bioavailability differed very obviously. The method used is simple and convenient. So UV-spectrophotometry is one of the methods for the assay of norfloxacin preparations in vitro and in vivo.