In order to find out the effects of different potassium (K) fertilizer on cadmium (Cd) in soil-crop system under the condition of reclaimed water irrigation, the field experiment was conducted to study the effects of different K fertilizer treatments on the Cd content of tomato plants, fruits, rhizosphere soil and non-rhizosphere soil. The results showed that under the condition of reclaimed water irrigation, applying K fertilizer could increase the yield of tomato fruits, the effect of KCl on the tomato fruit yield was more obvious than that of K₂SO₄, and the yield was increased by 6.10%~24.00% and 1.36%~13.16%, respectively, compared with the treatment without K fertilizer. The Cd content of tomato fruit in the treatment without K fertilizer was lower than that of the no fertilization treatment, but the decrease range was less than that of the treatment with K fertilizer. The Cd content of tomato fruit treated with KCl was lower than that treated with K₂SO₄, and the Cd content decreased by 58.33% and 8.33%, respectively, compared with the treatment without K fertilizer, and the content of Cd in all treatments did not exceed 0.05 mg/kg limit value. The pH value and the total Cd content of soil in the treatment without K fertilizer was lower than that in the treatment without fertilizer, but the decrease range was less than the treatment with K fertilizer. The available Cd increased. When KCl and K₂SO₄ were applied, the available Cd decreased compared with no fertilization treatment, and the total Cd content, available Cd content and the pH value in rhizosphere soil and non-rhizosphere soil were lower than those of treatment without K fertilizer. When the KCl was applied, the total Cd content of rhizosphere soil and non-rhizosphere soil decreased by 2.96%~3.11% and 5.75%~14.22%, respectively, and the available Cd content decreased by 10.75%~16.19% and 13.98%~28.74%, respectively. When the K₂SO₄ was applied, the content of total Cd in rhizosphere soil and non-rhizosphere soil decreased by 4.14%~5.90% and 8.10%~8.29%, respectively, and the available Cd content decreased by 15.97%~20.55% and 19.91%~24.70%, respectively. Therefore, under the condition of reclaimed water irrigation, the distribution and biological effectiveness of Cd in plant-soil system could be regulated by selecting appropriate K fertilizer. Compared with KCl, the application of K₂SO₄ could reduce the total Cd content and the available Cd content.