In this paper, we propose a new dynamic threshold commercial key escrow scheme (DTCKE) based on conic. Research of DTCKE schemes presents interesting problems. It not only effectively solves the conflicting between human privacies and authorized law enforcement access to suspectable communications, but also caters to some important requirements in real application including the needs to renew the system’s secret key, or to add/remove or update a key escrow agent, without leaking any information on the escrowed key and changing other key escrow agents’ secret shares. And previous key escrow schemes are based on either integer factorization or discrete logarithm problem (DLP), this scheme is based on conic and combines the merits of conic curve.