The selective laser melted TC4 alloy has been chemical polished in HF–H

2

O

2

solutions. The effects of chemical polishing time and H

2

O

2

concentration on the surface morphology

roughness

gloss

weight loss rate and thinning rate of the specimens during chemical polishing have been investigated. The result shows that the surface roughness of the specimen gradually decreases

while the gloss

the weight loss rate and the thinning rate of the specimen  increase with the increase of chemical polishing time; and with the increase of H

2

O

2

concentratio

n

the surface roughness of the specimen firstly decreases and then increases

while the gloss

the weight loss rate and the thinning rate firstly increase and then decrease. In particular

the optimal chemical polished surface of the specimen has been obtained at the HF：H

2

O

2

volume ratio of 1：5

the chemical polishing time of 8 min. After chemical polishing in the above optimal solution

the adhered powders of the specimen have been completely removed

with the surface roughness R

a

of (3.5±0.3) μm

and the gloss of (80.3±0.7) GU

and the surface quality of the specimen has been significantly improved compared to that of the asbuilt specimen (surface roughness of (13.3±0.8) μm

and the gloss of (0.9±0.3) GU). Moreover

the chemical polishing mechanism of titanium alloy in HF–H

2

O

2

system has been also discussed.