Excessive emissions of carbon dioxide and other greenhouse gases have seriously affected the ecological environment, public health, and the normal operation of the social economy, and the development of the low-carbon economy has become an international consensus. The policy norms are one of the important factors affecting the development of the low-carbon economy; however, the implementation of low-carbon economic policy in many countries has been inhibited. This study chose Liaoning Province of China for the case study, and the policy system, the policy tools, the administrative system, the low-carbon technology, and the low-carbon concept are found to be factors that led to the inhibition of the policy effectiveness of the low-carbon economy in Liaoning Province. We applied the modified Schweller Neoclassical Realist Theory to establish a multi-factor linkage model to demonstrate the overall relationship among various variables. The results show that the equilibrium of policy effectiveness of the low-carbon economy in Liaoning Province depends on different permutations of variables. We also discussed the problems of the policy system, the policy tools, the administrative system, the low-carbon technology, and the low-carbon concept that lead to policy effectiveness inhibition, and used the economic method to set a special mathematical model for maximizing the equilibrium of policy effectiveness of the low-carbon economy in Liaoning Province. In response to the problems of the above factors, strategies to promote the development of the low-carbon economy in Liaoning Province are proposed. This study enriches the research on the policy effectiveness of the low-carbon economy in China and provides some inspiration for the goal of carbon neutrality and other developing countries with high carbon emissions.