The synthesis of cadaverine from heterogeneous decarboxylation of L-lysine is of great significance for the industrial production of nylon 5X materials. However, it still remains as a great challenge with a low selectivity ∼50%. We herein report a strategy for selective decarboxylation of L-lysine via alkaline metal modification of heterogeneous catalysts, where the selectivity of cadaverine reaching 76% was obtained over K-Ru@FAU under optimized reaction conditions. K-Ru@FAU also exhibited high reactivity with a 100% conversion of L-lysine in one hour. Characterizations revealed that electrons transfer from alkaline metals to catalysts, leading to a greatly enhanced Lewis base properties of oxygen atoms with negative charges. It greatly facilitated chemical adsorption of L-lysine. Finally, reaction mechanism was proposed which contains chemical adsorption to carboxylate forms, activation to active surface carbonyl species, and decarbonylation to cadaverine. The alkaline metal modification provides a new route for directed decarboxylation of amino acids to primary amines.