The invention discloses a compaction shaping device for manufacturing a triaxial test specimen and a test method thereof. The device is totally divided into three parts; the first part is a pressurization device; the pressurization device is a jack placed on a device base; the second part is a shaping device; the shaping device consists of a support frame, a fixing base, a fixing round tube, a screw bolt and a combined round tube; the third part is a soil adding device; the soil adding device consists of a soil adding funnel and a compaction table; the three parts are tightly combined and jointly work. During test, the combined round tube is firstly fixed on the base; then, the corresponding weight of soil is weighed and is added into the combined round tube through the soil adding funnel;the compaction table is installed; the pressure of the jack is regulated for compaction. After the test block pressing is completed, the fixing round tube fixed on the support frame is released; thetest specimen can be obtained by taking out the combined round tube and unscrewing the screw bolt.