Quantum computing is different from classical computing based on quantum bits. With the development of Moore's law, the chip scale of classical computing is decreasing, and the quantum tunneling effect can not be ignored. In the future development of computer, we can either overcome the quantum characteristics and continue to promote classical computing; Or actively embrace the characteristics of quantum physics and directly use quantum effects to process information from the perspective of quantum computing. In other words, in classical computing, the reduction of size leads to the prominence of quantum effects and affects the development of classical computing; The quantum bit that uses the quantum effect brings a new computing mode and can realize the acceleration effect. Classical bits can only be in one of the two states of 0 or 1, while quantum bits exist in the form of 0 and 1 superposition, and can deal with the calculation of large-scale data through quantum superposition and entanglement. The superposition state means both 0 and 1. The evolution of qubit state corresponds to the rotation of state vector on Bloch sphere. Theoretically, a quantum computer with hundreds of qubits can process more calculations at the same time than the number of atoms in the known universe.