Quantum cryptography is the product of the combination of quantum theory and key science, and it is an important part of quantum secure communication. Quantum secret sharing (QSS) is one of the core contents of quantum cryptography. It can transfer keys between two parties that are not fully trusted. At present, it has attracted the attention of researchers at home and abroad. A novel BB84 protocol-based quantum secret sharing with decoy states is proposed. A series of weak coherent pulses generated by Alice are polarizedly modulated, then separated as two series of weak coherent pulses by a beam splitter. The two series of weak coherent pulses are intensity modulated further by a decoy modulator, and then sent to Bob and Charlie. Bob and Charlie measure the weak coherent pulses and announce the results. Based on the results, Alice, Bob and Charlie can obtain the secure key after basis reconciliation, error correction and privacy amplification. As the numbers of qubit generating and measuring devices are reduced greatly, the scheme provides a practical way for QSS technique with less cost.