For more than half a century, most of the plasma scientists have encountered a violation of the conservation laws of charge, momentum, and energy whenever they have numerically solve the first-principle equations of kinetic plasmas, such as the relativistic Vlasov-Maxwell system. This fatal problem is brought by the fact that both the Vlasov and Maxwell equations are indirectly associated with the conservation laws by means of some mathematical manipulations. Here we propose a quadratic conservative scheme, which can strictly maintain the conservation laws by discretizing the relativistic Vlasov-Maxwell system. A discrete product rule and summation-by-parts are the key players in the construction of the quadratic conservative scheme. Numerical experiments of the relativistic two-stream instability and relativistic Weibel instability prove the validity of our computational theory, and the proposed strategy will open the doors to the first-principle studies of mesoscopic and macroscopic plasma physics.where ρ and J are the charge and current densities, respectively. However, Eqs. (5) and (6) are naturally satisfied when the law of charge conservation and the inexistence of the magnetic monopole are assumed. Fortunately, these principles are derived from the 0th-order moment equation of Eq.(1). Therefore, we do not need to solve Eqs. (5) and (6) when solving Eqs. (1), (3), and (4). Modern numerical investigations of kinetic plasmas can be characterized in two ways. The first one is a particle-in-cell (PIC) method [1], which solves the equations of motion of charged particles, such as ions and electrons, instead of the Vlasov equation. In the PIC, the equations of motion are coupled with the Maxwell equations using some of the field interpolation techniques. Another approach is to discretize the Vlasov equations directly by using the finite-difference method, spectral method, and so on (hereafter, called "Vlasov simulation"). However, these numerical methods have a fatal problem; the conservation laws of charge, momentum, and energy are violated in principle when the governing equations are discretized. The term "numerical heating" is a nightmare among PIC users, which implies that the total energies in PIC simulations increase infinitely even if there is no physical energy source. To overcome this issue, many mathematical investigations were performed on the conservation property of the first-principle kinetic simulations, and significant progress was made mainly in the 2010s. Crank-Nicolson time integration is one of the key structures in the construction of conservative PIC methods; recent studies have employed it in energyconserving [2, 3, 4], charge-energy-conserving one-dimensional one-momentum-component (1D1P) [5], onedimensional three-momentum-components (1D3P) [6], and two-dimensional three-momentum-component (2D3P) [7] PIC methods. A study discretized the equations of motion with a leap-frog method, while the Maxwell equations were solved with the Crank-Nicolson method; the total energy was strictly conserv...