Abstract: With the rapid development of blockchain applications, light clients have become essential components in digital wallets and cross-chain communication due to their minimal storage and computational overhead. However, existing light client protocols face significant limitations in terms of storage and communication costs, security, and compatibility across different consensus mechanisms. We propose DecXClient, a general and secure light client protocol compatible with multiple consensus models. DecXClient introduces a dynamic validator set election mechanism based on chain quality attributes, eliminating reliance on trusted third parties. By integrating weighted multi-signature schemes, it enables a concise and efficient proof generation paradigm that enhances anti-fraud resilience while reducing resource consumption. Without depending on centralized relays, DecXClient maintains sublinear communication and storage complexity, effectively mitigating Eclipse attacks and other security threats. Experimental evaluations using real blockchain network environment demonstrate that the protocol produces state proofs as small as 1248 bytes—significantly outperforming existing schemes. The average proof generation latency ranges from 266.4 milliseconds to 2.5 seconds, with negligible verification time. These results validate the feasibility and practicality of DecXClient, offering a robust solution for lightweight blockchain access across diverse application scenarios.