Abstract: The single crystal growth rates of potassium sulfate in pure aqueous solution under different conditions were determined by photomicrography in a flow system for crystal growth. The effects of the main controlling factors, such as supersaturation, crystal size, solution velocity and crystal growth temperature, on crystal growth rates of potassium sulfate were discussed in detail by using non-linear regression from the experimental data, and several empirical relationships were given.The results showed that the growth rates of crystals increased with supersaturation, crystal size, solution velocity and temperature. Moreover supersaturation was the most important controlling factor influencing growth rates of crystals,crystal size and solution velocity were the secondary and temperature was the least. Furthermore, It was found that the growth rate of crystals along the ［100］ crystallographic axis was higher than that along the ［001］ in the same condition. The effect of every factor on crystal growth rates along the ［100］ crystallographic axis was stronger than that along the ［001］.