Photo therapy for cancer has attracted massive attentions due to the advantages of excellent selectivity, non-invasion and low toxicity. However, the application of traditional photo agents in cancer therapy is limited by the defects of single function, poor water solubility, and weak targeting to tumors. Herein, a tumor extracellular microenvironment responsive and photo-sensitive nanocomposite based on the combination of nitrogen doped carbon dots (N-CDs), histidine, and hemin was developed, possessing high-performance phototherapy for cancer. The histidine grafted nanocomposites could undergo intriguing charge conversion from negative-charged surface to positive one in mildly acidic tumor extracellular microenvironment (pH similar to 6.5), leading high affinity to negatively charged cancer cell membrane, which resulted in enhanced targeting ability of the nanocomposites. Meanwhile, the photothermal property of N-CDs and photodynamic ability of hemin were simultaneously enhanced via the fluorescence resonance energy transfer (FRET) effect in CC NCs, which endued the synthesized nanocomposites with excellent bi-phototherapy for cancer cells. Moreover, the as-prepared nanocomposites could deliver plasmid into tumor cells for effective gene transfection, which possessed potential application in gene therapy. The present work demonstrates that the obtained nanocomposites could achieve multimodal cancer therapies and provides the inspiration for the design and synthesis of other multifunctional materials.