Current identity-based partially blind signature scheme or the security is not high, or less efficient. Aiming at the defect, through analysis for cryptography and algorithm design, the paper presents an new ID-based partially blind signature scheme with only one bilinear pairing without trusted Private Key Generator (PKG). The proposed scheme has been proved to be strong blindness and be secure against existential forgery on adaptively chosen message and ID attack, and against attack from un-trusted PKG, and be more efficient. Its security relies on the hardness of l-Strong Diffie-Hellman problem (l-SDHP). The difference of the scheme with other likely schemes has been done.