MicroRNA, a short non-coding RNA chain, plays important roles in post-transcription regulations by targeting gene 3'UTR through sequence complementary principle. Previous researches showed that microRNAs play important roles in heart development process. Heart development of the Antarctic icefish (Chionodraco hamatus) shows compensatory physiological enlargements due to the lack of functional red blood cells in the body. Previous studies suggested that microRNAs specifically expressed in the C. hamatus heart may be associated with icefish compensatory physiological enlargement. In this study, according to the highly expressed miR-210-5p, we studied the heart development functional mechanism of miR-210-5p by using zebrafish microinjection and gene's target prediction. The results showed that overexpression of miR-210-5p in 72hdf zebrafish embryos could affect zebrafish heart development, characterized by cardiac malformations such as pericardial edema. QRT-PCR analysis showed that overexpression of miR-210-5p in zebrafish downregulated heart development marker genes including bmp4, smad1, gata6, tbx2b. Western blot analysis found that the protein expression levels of BMP4, BMP2, SMAD1, GATA6 and TBX2B were downregulated. According to the bioinformatics prediction and GFP fluorescence analysis, we found tbx20 may be a target of miR-210-5p. Therefore, we speculated that miR-210-5p might inhibit tbx20 gene expression and might suppress heart development of C. hamatus through bmp/smad pathway.