The invention discloses a preparation method for a heterojunction nano-photocatalysis material and application of the material. The nano-photocatalysis material a heterojunction catalyst formed by performing a double hydrothermal method on SrTiO3 and Bi2MoO6; the preparation method for the nano-photocatalysis material comprises the following steps: adding an NaOH solution after TiCl4 and an Sr(OH)2.8H2O solution are mixed under ultrasonic stirring, putting an obtained precursor in a hydrothermal kettle for heating, and washing and drying a product to obtain nanoscale SrTiO3; absolutely dissolving bismuth salt in an SrTiO3 solution, then, dropwise adding a molybdate solution, putting in the hydrothermal kettle for heating after ultrasonic stirring, and washing and drying a product obtain the SrTiO3/BiMoO6 nano-photocatalysis material. According to the preparation method disclosed by the invention, the heterojunction catalyst with efficient visible-light catalytic activity is prepared at low cost and with a simple process; the catalyst is capable of degrading rhodamine B and organic dye with other color development radicals under visible light.