The present invention relates to a salt of μ-opioid receptor (MOR) agonist, fumarate I crystal form thereof and preparation method thereof. Specifically, the present invention relates to a salt of (1S,4S)-4-ethoxy-N-(2-((R)-9-(pyridin-2-yl)-6- Oxaspiro [4.5] decan-9-yl)ethyl)-1,2,3,4- tetrahydronaphthalen-1-amine, fumarate I crystal form thereof and preparation method thereof. The compound of the formula (I) of the present invention has good solubility, its I crystal form has good crystal stability, and can be better used for clinical treatment.本發明涉及一種阿片樣物質受體（MOR）激動劑的鹽、其富馬酸鹽I晶型及製備方法。具體地，本發明涉及(1S,4S)-4-乙氧基-N-(2-((R)-9-(吡啶-2-基)-6-氧雜螺[4.5]癸-9-基)乙基)-1,2,3,4-四氫萘-1-胺的鹽、其富馬酸鹽I晶型及其製備方法。本發明式（I）化合物具備良好的溶解性、其I晶型具備良好的晶型穩定性，可更好地用於臨床治療。
