In order to realize the nanotheranostics and reduce the toxicity of nanotheranostics agents to healthy tissues/organs, we constructed a novel nanotheranostics agents (Gd-DTPA-CS@β-CD@Dox) for MR imaging and Cancer treatment. Renal-clearable nanocomposites made it possible to overcome the long-term toxicity by accumulation in healthy living body. High uptake of the as-synthesized Gd-DTPA-CS@β-CD@Dox was achieved due to the longer blood circulation time. Moreover, the nanotheranostics agents possessed excellent performance in MRI. The nanotheranostics agents demonstrated a PH sensitive drug release. Such functional nanotheranostics agents applicable in highly integrated bio-modal imaging and multiple therapeutic functions may have great prospects in clinical practice.