¹⁴C-butachlor and ¹⁴C-oxadiazon could be released from four kinds of CR formulations into water respectively, and the release percentage of each herbicide increased with time, which could be expressed by regression equations (very obvious positive relationship). The release percentages of ¹⁴C-herbicides from CR formulations were related to herbicide, CR formulation and water type. Total recovery including ¹⁴C-released and ¹⁴C-left in formulations for each ¹⁴C-herbicide was high at the 56th day after treatment. Some of the released ¹⁴C-butachlor in water could be hydrolysed although under dark condition. The rate of hydrolysis was influenced by water type and formulations.