Based on metastable beta titanium alloy Ti-55531, the structure of the sample was obtained by solution quenching above the β phase. Room temperature compression was performed using a Gleeble3800 thermal simulation test machine and a 6.3MN forging simulator. OM, XRD and TEM were used to observe the deformed structrures after different strains. The results show that the maximum compression of 30% room temperature compression true-stress and true-strain curve at the strain rate of 0.0005s-1 is mainly divided into two stages that are elastic deformation stage and plastic deformation stage with obvious strain hardening stage. However, the maximum compression of 30% room temperature compression true-stress and true-strain curve at the strain rate of 0.1s-1 is mainly divided into two stages that are elastic deformation stage and plastic deformation stage without obvious strain hardening stage. Both of them do not have double yield phenomenon. The deformation structures have little different at the different strain rates of the same reduction. The deformation mechanism is dominated by slip. With the strain increasing, the dislocation density increases gradually and the dislocation tangles and shears appear. Strain induced martensite transformation occurs at the compression of 30% and the strain rate of 0.0005s-1 and 0.1s-1. The compression of 50% and 60% also appears strain induced martensite transformation at the strain rate of 10s-1.