Biological soil crusts (biocrusts) play critical roles in maintaining soil fertility and conserving soil and water in arid and semi-arid area, and in situ remediation that mediated by biocrusts is perhaps one of the key process to control heavy metal(loid)s pollution in mine tailing ponds. However, how the biocrusts regulate behaviours of heavy metal(loid)s (i.e., Pb, As, Zn) in tailing wetlands are largely unknown. Here we examined contents of heavy metal(loid)s in biocrusts and suspended particles of mine tailing effluent, in order to reveal probable relationships of heavy metal(loid)s between immobilization in biocrusts and spatial distributions in effluent particles. Results showed that heavy metal(loid)s were largely accumulated in biocrusts (i.e., Pb, 0.42 g kg^-1; As, 23.7 g kg^-1; Zn, 11.1 g kg^-1), some of which were even significantly higher than tailing sand. Concentrations of Pb (0.32-1.04 g kg^-1), As (3.60-32.1 g kg^-1) and Zn (2.36-23.2 g kg^-1) were high in fine suspended particles of tailing effluent wherever they were distributed in the tailing wetland system, and heavy metal(loid)s contents in effluent particle decreased significantly along the downstream where biocrusts were also present. In addition, contents of Fe were as high as 131 g kg^-1 in biocrusts, and 63.3-223 g kg^-1 in effluent particles, respectively, in the neutral (6.05-7.74) system. Overall, our study demonstrates that biocrusts have a perfect performance on heavy metal(loid)s immobilization, and fine particles in tailings effluent might be the foremost source of metal(loid)s in biocrusts. This study was supported by National Key R&D Program of China (No. 2018YFD0800700); National Natural Science Foundation of China (No. 41671313; 41703073); Science and Technology Planning Project of Guangdong Province, China (No. 2016A020221012; 2014A050503032; 2017B020216008); The 111 Project of China (No. B18060).