By applying the concept of selfcertified signcryption to multiproxy signature,a new selfcertified multiproxy signcryption scheme without trustworthy system authority is constructed, and its security relies on the hardness of discrete logarithm problems in the finite field. The new scheme has the merits of selfcertified signcryption; moreover, an original signcryter can authorize a group of proxy signcrypters, and the multiproxy signcryption is generated by the cooperation of all the proxy signcrypters. The constructed algorithm is a secure and practical multiproxy signcryption scheme which has lower computation complexity and higher communication efficiency.