Implementations of this specification provide a method and apparatus for transaction scheduling in a blockchain. An example method performed by a node in the blockchain includes receiving a first privacy transaction, and determining a data volume of the first privacy transaction; determining a first summation value by adding the data volume of the first privacy transaction to a data volume of all privacy transactions in a buffer queue, and adding the first privacy transaction to the buffer queue; receiving a second privacy transaction, and determining a data volume of the second privacy transaction; determining a second summation value by adding the data volume of the second privacy transaction to a data volume of all privacy transactions in the buffer queue, and packaging all privacy transactions in the buffer queue and transferring the packaged privacy transactions into a trusted environment; and adding the second privacy transaction to the buffer queue.