Docetaxel is an adjuvant chemotherapy drug widely used to treat multiple solid tumors, however its toxicity and side-effect limits its clinical efficacy. Herein, the docetaxel-loaded solid lipid nanoparticles (DSNs) were developed to reduce systemic toxicity while still keeping its anti-cancer activity. To evaluate its anti-cancer activity and toxicity and understand the molecular mechanisms of DSNs, different cellular, molecular and whole genome transcription analysis approaches were utilized. The DSNs showed lower cytotoxicity compared with the commercial formulation of docetaxel-Taxotere and induced more apoptosis at 24 h treatment in vitro. It can cause the treated cancer cells arrested at G2/M phase in a dose-depend manner as Taxotere. The DSNs can also suppress tumor growth very effectively in a murine breast cancer model. Systemic analysis of gene expression profiles by microarray and the following verification experiments suggested that both DSNs and Taxotere regulate expression of series genes and these genes functions involved in DNA replication, DNA damage response, cell proliferation, apoptosis and cell cycle regulation. Some of these genes expressed differentially at protein level although their transcription level was similar under TAX and DSNs treatment. Moreover, DSNs improved main side-effect of Taxotere by greatly lowering myelosuppression toxicity to bone marrow cells from mice. Taken together, our results expound the anti-tumor efficacy and the potential working mechanisms of DSNs in its anti-cancer activity and toxicity, which provide a theoretical foundation to develop and apply more efficient docetaxel formulation to treat cancer patients.