The paper presents the realization of a high-fidelity controlled-Z (CZ) gate using a double-transmon coupler (DTC) scheme, which aims to achieve both suppressed residual interaction and fast high-fidelity two-qubit gates. The DTC consists of four transmons: two data qubits (Q1 and Q2) and two coupler transmons (C3 and C4). The ZZ interaction between the qubits can be controlled and suppressed by tuning the magnetic flux through the DTC's loop. The authors demonstrate experimentally that the DTC can achieve fidelities of 99.92% for a CZ gate and 99.98% for single-qubit gates. The performance of the DTC is attributed to its high coherence, large on-off ratio of the qubit-qubit coupling, and optimized control pulse shape. The study also includes a detailed analysis of the CZ gate error, showing that the residual errors are dominated by incoherent errors, which are positively correlated with the gate length. The DTC scheme is promising for implementing NISQ applications and quantum error correction due to its advantages in frequency-collision probability, flexible spatial arrangement, and simplified control degrees of freedom.The paper presents the realization of a high-fidelity controlled-Z (CZ) gate using a double-transmon coupler (DTC) scheme, which aims to achieve both suppressed residual interaction and fast high-fidelity two-qubit gates. The DTC consists of four transmons: two data qubits (Q1 and Q2) and two coupler transmons (C3 and C4). The ZZ interaction between the qubits can be controlled and suppressed by tuning the magnetic flux through the DTC's loop. The authors demonstrate experimentally that the DTC can achieve fidelities of 99.92% for a CZ gate and 99.98% for single-qubit gates. The performance of the DTC is attributed to its high coherence, large on-off ratio of the qubit-qubit coupling, and optimized control pulse shape. The study also includes a detailed analysis of the CZ gate error, showing that the residual errors are dominated by incoherent errors, which are positively correlated with the gate length. The DTC scheme is promising for implementing NISQ applications and quantum error correction due to its advantages in frequency-collision probability, flexible spatial arrangement, and simplified control degrees of freedom.