In the principal-agent system where local governments commission recyclers to recycle and dispose of low-value recyclables, the recycler's capacity type and effort level are their private information, resulting in the problem of double asymmetric information. The recycler's fairness preference also has an impact on the implementation effect of the local government's commission contract. This paper considers the design problem of incentive mechanism for recyclers with horizontal fairness preference under double asymmetric information, builds incentive mechanism models for the recycling and disposal system of low-value recyclables under complete rationality, disadvantageous and dominant unfairness, characterizing the optimal contract characteristics. The results show that: subsidies based on quantity under disadvantageous unfairness can help offset the negative effects of jealousy and motivate recyclers to put in the best effort level. While under the dominant unfairness preference, the recycler's income from accepting the contract is higher than the average income in the same industry. At this time, it should be changed to a fixed subsidy as the main method to ensure the basic interests of recyclers, which can better mobilize the enthusiasm of recyclers. At the same time, it is found that under the optimal contract provided, the higher the intensity of the recycler's disadvantageous unfairness preference or the lower the intensity of the recycler's dominant unfairness preference, the more sufficient the recycling and disposal of low-value recyclables, and the higher the profits of both the principal and the agent.