A high density spherical nano lithium iron phosphate material, a preparation method thereof, and a lithium ion battery containing the same are provided. The preparation method comprises the following steps: (1) pre-sintering a lithium resource, iron phosphides, adulterant, and a carbon source with protective gas after dry mixing; (2) mixing a pre-sintering material, dispersant, and deionized water, and performing ultra fine grinding; (3) performing spray drying on a sizing agent obtained by ultra fine grinding, to obtain a spherical nano lithium iron phosphate precursor; and (4) performing chemical vapor deposition coating on the spherical nano lithium iron phosphate precursor obtained in step (3), to prepare the high density spherical nano lithium iron phosphate material. A primary particle size of the lithium iron phosphate material prepared in the present invention is not large, and a powder conductivity may reach 10.1 S / cm, so that a material capacity, low temperature, rate performance, and fabrication and cycling performance may be well balanced.