Relating to an opioid receptor agonist (1S,4S)-4-ethoxy-N-(2-((R)-9-(pyridin-2-yl)-6-oxaspiro[4.5]deca-9-yl)ethyl)-1,2,3,4-tetrahydronaphthalen-1-amine fumarate salt, a fumarate saltIcrystal form thereof, and a preparation method and an application therefor.