The present invention discloses a salt derivative of 1-(3-methanesulfonamidobenzyl)-6-methoxy-7-benzyloxy-1,2,3,4-tetrahydroisoquinoline shown in formula I. The salt derivative has a solubility in water of not less than 3.0 nmol/mL or 1.8 mg/mL:The salt derivative has a solubility in water of not less than 3.0 nmol/mL or 1.8 mg/mL