Objective: To isolate, purify and culture fibroblastic reticular cells (FRCs) of mouse in spleen, to develop a reliable and robust method to immortalize primary mouse FRCs, to filter stable FRCs cell lines, to prove that the clones can be infected by SFTSV in vitro. Methods: After purifying FRCs by fluorescence activated cell sorting (FACS) from autoMACS-enriched stroma cells of mouse spleen, we infected FRCs by simian virus 40 large T antigen in vitro, screened the FRCs clones with puromycin, compared primary and immortalized FRCs by RNA sequencing(RNA-seq) technology, infected the clones with severe fever with thrombocytopenia syndrome virus (SFTSV) in vitro. Results: We succeed in culturing purified FRCs from spleen, isolated four stable FRCs clones, two of which have a purity of 99%, survived for more than 50 passages, express the key FRCs marker podoplanin and do not express CD31 and CD45. Clone 01 lost the typical FRCs-like morphology, the rate of expansion of which is quite different from that of primary FRCs and Clone 02. Clone 02 can be infected with SFTSV, which has the same gene expression pattern and immunophenotype with primary FRCs. Conclusions The stable FRCs clone Clone 02 has FRCs-like morphology and express key FRCs surface markers podoplanin (GP38 or PDPN) and do not express endothelial cell markers CD31 and leukocyte common antigen CD45. The RNA expression profiles identified by RNA-seq are also characteristic of FRCs. Infected with SFTSV in vitro, Clone 02 will be a new platform to study SFTSV.