Four kinds of heat treatment processes were used to study the effect on the microstructure and properties of the TC4ELI big-diameter titanium alloy tubes. The results show that after the processing of 750 ℃×1 h/AC,the widmanstatten structure is acquired,the impact toughness and fracture toughness are much higher,but the tensile strength is the lowest; after the processing of 900 ℃×1 h/AC,the widmanstatten structure with fuzzy grain boundary is obtained,the impact toughness and fracture toughness are as high as that of the previous processing,and the tensile strength is increased; after the processing of 930 ℃×1 h/WQ+580 ℃×6 h/AC,the widmanstatten structure with very fine α lamellas is obtained,the fracture toughness(968 MPa·m1/2),tensile strength(892 MPa),reduction in area(42%) and elongation(160%) are the highest among the properties after four kinds of heat treatment processes,while the impact toughness is decreased seriously; after the processing of 930 ℃×1 h/WQ+650 ℃×6 h/AC,the widmanstatten structure with α phase lamellas interwovened is acquired,the tensile strength and fracture toughness are also higher,but the impact toughness is the lowest value.