Middleware Security - An evolvable hardware platform (EHWP) based on programmable devices can realize specific hardware function structures by changing the bitstreams. As EHWP becomes more and more widely used in security chips, issues related to hardware security have received focused attention, especially hardware Trojans (HTs). However, current research has focused on implementing defense against HTs in the underlying hardware, with very sparse mitigation solutions for HTs in the overlay/middleware layer. Given this, we attempt to implement an HTs mitigation solution using the characteristics of the EHWP. Specifically, we utilize evolutionary algorithm (EA) to explore new circuit structures to replace the HTsinfected resources, thus avoiding the related security issues. The experimental results show that the scheme proposed in this paper can effectively mitigate the HTs on EHWP.