A novel mixed micelle made of Tween 80 and soybean phospholipids (S80) was prepared and used as the delivery system for paclitaxel (PTX), with the purpose of improving the stability, therapeutic index, and security of PTX in comparison with Taxol® injection. The micelle size, morphological features, dilution stability, and critical micelle concentration (CMC) were measured. The in vitro antitumor activity, pharmacokinetics, and hemolysis effect of the optimal PTX-loaded mixed micelles (PTX-M) were evaluated and compared with Taxol®. The results showed that PTX-M was more stable than Taxol® upon dilution. PTX-M had a higher antitumor efficacy against HeLa and A549 cells than that of Taxol®. The plasma AUC of PTX-M was 1.3-fold higher than that of Taxol® and the hemolysis test revealed that PTX-M was safe for intravenous injection. In conclusion, PTX-M had a higher dilution stability and antitumor efficacy than Taxol®, but significantly reduced the toxicity while improving the bioavailability of PTX. Therefore, Tween 80-S80 mixed micelles could be a promising drug carrier for intravenous administration of PTX.