Objective To prepare 188 Re-c ( CGRRAGGSC) by different labeling methods, and compare the stability and targeting ability for triple-negative breast cancer (TNBC). Methods 188 Re la-beled c( CGRRAGGSC) was prepared by direct method ( pre-tinning method) and indirect method (the hydrazinonicotinamide (HYNIC) conjugated c(CGRRAGGSC) peptide) respectively. Quality control and sta-bilities of radiolabeled probes were measured. Nude mice bearing TNBC cells (MDA-MB-468) were estab-lished and used for detecting the distribution in vivo. Tumor/ non-tumor (T/ NT) ratios of radiolabeled probes prepared by direct method and indirect method were compared to certify the targeting ability and biological activi-ty. Two-sample t test was used to analyze the data. Results The labeling rate of 188Re-c(CGRRAGGSC) by di-rect method was >87％, but the serum stability was poor (the degradation rate was about 40％ at 2 h), and the T/ NT ratio was 2.82±0.23 (n=3) at 2 h. On the other hand, the labeling rate of 188Re-HYNIC-c(CGRRAGGSC) by indirect method was 61％, while the serum stability was about 10％ at 2 h, and T/ NT ratio was about 6. 27±0.51 (n= 3) at 2 h, which was significantly higher (t = 2.13, P<0.05). Conclusions The direct method may have higher labeling rate than the indirect method, but the radiolabeled compound by the direct method has poor stability and tumor targeting ability. 188 Re-HYNIC-c(CGRRAGGSC) prepared by indirect method may have remarkable advantages on stability and biological activity.