Rydberg atoms are important building blocks for quantum technologies, and because of their unique tunable quantum properties, they possess new applications in quantum computing, quantum communication, and quantum sensing. Besides the widely-used few-photon resonant excitation for the specific Rydberg state, multiple Rydberg states can be populated coherently and efficiently through the frustrated tunneling ionization or the Coulomb potential recapture effect in a strong laser field. The excitation of Rydberg states in a strong field provides an opportunity for realizing the ultrafast quantum control on Rydberg atom and bridging the gap between strong field physics and quantum information technology. Using the classical trajectory Monte Carlo method and Qprop package to solve time-dependent Schrödinger equation, we calculate the population of Rydberg states. Our results show that the population increases with the increase of parameter of the asymmetric laser envelope. Based on the quantitative rescattering theory, the calculated time-dependent recapture rate is negatively related to the laser envelope and the residual laser interaction time, which is termed the envelope effect. Combined with the carrier-wave effect, an analytic formula can be used to calculate the Rydberg state population: $ Y(t) \propto $$ W_0\left(t\right) \dfrac{t-\tau+c}{f\left(t\right)} \cos \left(\omega t+\phi\right) . $ This result opens the way to enhancing the generation of Rydberg states by using the laser envelope control, which is beneficial to the future quantum technology based on the Rydberg states generated in the strong laser field.