This paper investigates the problem of small disturbance stabilization of the directly connected hybrid system of grid-forming(GFM) and grid-following(GFL) converter without taking into account the interconnection impedance. To explore the advantages of this direct connection structure, firstly, a state-space model of the directly connected hybrid system is established, based on which the broadband oscillation characteristics of the hybrid system are compared with the standalone GFM/GFL under different short-circuit ratio(SCR) by obtaining the participation factor and plotting the root trajectory, and the dynamic frequency control characteristics are investigated by simulation. Then, based on the study of the effect of virtual inductance(VI) on low and medium frequency oscillations, the improved control of VI with the introduction of low-pass filtering differential term is proposed to improve the system stability. Finally, the accuracy and effectiveness of the theoretical analysis and the improved control strategy are verified based on time-domain simulation.