Photothermal cancer therapy have attracted great attention as a new-rising therapeutic modality along with the great progress in nanomedicine.In this talk,I will present our newest researches on designing multifunctional photothermal conversion agents for cancer theranostics.Biosynthetic magnetosomes were used as a photothermal conversion agent for cancer theranostics under the guidance of imaging.We researched how to assembly a complicated composite inorganic nanocapsule without influence their performance for combination therapy and multimodal diagnostic imaging.