Expert involvement is usually regarded as one of the causes of policy changes. However, how does the nature of policy change, in turn, influence expert involvement? This study constructs an analytical model by adopting and developing policy network and principal-agent theories, suggesting that expert involvement can be regarded as the result of the inherent characteristics of policy change in the Chinese policy process. Two key characteristics of policy change, namely ‘loss embeddedness’ and ‘knowledge complexity’, are employed to form four types of policy changes. Empirically, a comparative study with four policy change cases illustrates that Chinese experts adopt four behavioural strategies, such as linear access, outside-in enlightenment, deprofessionalized campaign, and locked-out, in different types of policy change. These policy change cases include the new-type rural cooperative medical care system, the new urban medical care system, revocation of detention and repatriation system, and the new economically affordable urban housing policy.