<i>Objective:</i> To research the expression characteristic and clinical significance of the serum bone morphogenetic protein 6 (BMP6) at the lower expression condition of serum C-reactive protein (CRP) and Hepcidin (Hepc) in patients with tumor-related anemia. <i>Methods:</i> 113 hospitalized tumor patients from October 2019 to June 2020 and 20 healthy volunteers (control group) were recruited. We used enzyme-linked immunosorbent assay (ELISA) to determine the levels of BMP6, soluble-hemojuvelin (s-HJV) and Hepc, Electrochemiluminescence method to determine SF level, and particle-enhanced immune transmission turbidity method to determine CRP level, then analyzed their expression characteristics, correlations and clinical significance. <i>Results:</i> (1) The levels of BMP6, Hepc and CRP of anemia group were respectively 426.18±202.83mg/mL, 6.58±5.41ug/L and 19.10±18.24mg/L, which were all higher than 334.37±171.32mg/mL, 4.60±2.28ug/L and 3.62±3.46mg/L of non-anemia group (<i>t</i>=2.5804, 2.4750 and 3.4144, <I>P</I><0.01, <I>P</I><0.05 and <I>P</I><0.01, respectively). (2) The level of s-HJV was 0.71±0.28ng/mL, which was obviously lower than 1.07±1.01ng/mL (<i>t</i>=2.6529, <I>P</I><0.01) in non-anemia group. (3) There were negative correlations between BMP6 and both Hb and s-HJV (respectively <i>r</i>=-0.2807, <i>t</i>=3.0812 and <i>r</i>=-0.2497, <i>t</i>=2.7230, respectively, <I>P</I> both <0.01), but there were no correlations between BMP6 and CRP, Hepc and SF. (4) Hepc was positively correlated with both CRP and SF (<i>r</i>=0.2004, <i>t</i>=2.0660 and <i>r</i>=0.3089, <i>t</i>=3.1045, <I>P</I><0.05 and <I>P</I><0.01, respectively). Hepc was negatively correlated with Hb (<i>r</i>=-0.2524, <i>t</i>=2.7525, <I>P</I><0.01). Hepc had no correlation with s-HJV (<I>P</I>>0.05). (5) The BMP6 in the normal CRP group was 461.86±142.91 mg/mL, which was significantly higher than 364.51± 129.84 mg/mL in elevated CRP group (<I>F</I>=11.35, <I>P</I><0.01). (6) Hepc, s-HJV and SF in the normal CRP group were 5.17±3.49ug/L, 0.69±0.26ng/mL and 149.89±142.34ng/mL, respectively, which were all significantly lower than 9.02±7.14ug/L, 0.76±0.33ng/mL and 288.36±254.51ng/mL in the elevated CRP group (<I>F</I>=9.56, 4.67 and 2.84, <I>P</I>=0.000, 0.09, 0.046, respectively). <i>Conclusions:</i> When tumor patients with anemia is in a low-level condition of CRP and Hepc, the high expression of BMP6 is an important cause for the occurrence and development of anemia.