As a potential amendment, biochar has attracted considerable attention for its impact on soil microbial communities. However, there is little consensus regarding the impacts of biochar derived from invasive plants on microbial communities in coastal saline wetland soils. In this study, we used Juglans regia biochar (JBC) and two other invasive plant biochar, Spartina alterniflora biochar (SBC) and Flaveria bidentis biochar (FBC) to saline soils at rates of 1%, 3%, and 5% (w/w). The results demonstrated that the application of biochar led to a reduction in microbial community diversity, particularly evident in the 5% SBC and FBC treatments. Furthermore, the 5% FBC treatment resulted in a notable decline in community richness. With regard to species composition, the addition of SBC and FBC resulted in a notable impact on the relative abundance of Acidobacteria in comparison to JBC. Additionally, 5% SBC led to a reduction in the relative abundance of Bacteroidetes by 21.49%-23.90%, and 5% FBC reduced the relative abundance of Nitrospirae by 14.71%-17.86%. The addition of biochar enhanced the overall complexity of the community. Specifically, adding 5% SBC boosted the complexity of the microbial network and encouraged cooperative relationships among microorganisms. However, this community became more vulnerable to environmental changes and exhibited weaker anti-interference capabilities. Moreover, 5% JBC and 5% SBC altered the community assembly process from deterministic to stochastic. We emphasize the importance of carefully selecting biochar types during soil remediation, with particular attention to the application of high concentrations of biochar. This paper lays the groundwork for long-term practice in soil remediation through the approach of "treating waste with waste".