This paper presents a visual programming environment for users to develop their own defined icon‐based Chinese input methods. It will show the following four aspects. First, Chinese characters are concrete icons (decomposition graphs or webs). Second, a grammar that generates the above mentioned webs is a context‐free web grammar. Third, an icon‐based Chinese input method defines semantic rules to the production rules of the web grammar which then becomes an attributed web grammar. Fourth, a Chinese input simulator is a machine that accepts these webs. Developing such a simulator can be regarded as the construction of a user‐defined application program under the proposed visual programming environment. This paper also shows that form‐based visual languages included in the environment can be used to specify ways of evaluation and simulation in the user‐defined simulator.