To improve the inefficiency of the existing key distribution protocols in the secure broadcasting, an ideal multi-recipient public key encryption scheme to achieve the secret broadcasting is proposed. Based on Shamir’s threshold secret sharing scheme, a multi-recipient public key encryption scheme of the IND-CPA security is proposed on bilinear pairing on elliptic curve. And then, extension is made on the proposed scheme to construct a new multi-recipient public key encryption scheme with the IND-CCA2 security. Based on the Bilinear Decisional Diffie-Hellman assumption and the Gap Bilinear Diffie-Hellman assumption, their security claimed above is proved. At the same time, analyses are made on the correctness and performance of the scheme. Analyses show that the proposed scheme is a efficient and secure public-key encryption scheme, in which, a ciphertext encrypted by an encryption key can be decrypted by a number of decryption keys. This makes it play an important role in many applications. Especially in the secure broadcasting, it can be applied to securely broadcast sensitive information in an unsafe and open network situation.