Disclosed are a novel tetrahydroisoquinoline compound, a method for preparing intermediates thereof, a pharmaceutical composition thereof and the use thereof. The tetrahydroisoquinoline compound of the present invention has a good inhibitory effect on phosphodiesterase (PDE4), and can be used in the prevention, treatment or auxiliary treatment of multiple diseases associated with the activity or expression of phosphodiesterase, especially PDE4-associated immune and inflammatory diseases, such as psoriasis and arthritis. (I)