Coherent control of molecular dissociation in ultrafast strong fields has received considerable attention in various scientific disciplines, such as atomic and molecular physics, physical chemistry, and quantum control. Many fundamental issues still exist regarding the understanding of phenomena, exploration of mechanisms, and development of control strategies. Recent progress has shown that manipulating the spectral phase distribution of a single ultrafast strong ultraviolet laser pulse while maintaining the same spectral amplitude distribution can effectively control the total dissociation probability and branching ratio of molecules initially in the ground state. In this work, the spectral phase control of the photodissociation reaction of chlorobromomethane (CH₂BrCl) is studied in depth by using a time-dependent quantum wave packet method, focusing on the influence of the initial vibrational state on the dissociation reaction. The results show that modifying the spectral phase of a single ultrafast pulse does not influence the total dissociation probability or branching ratio in the weak field limit. However, these factors exhibit significant dependence on the spectral phase of the single ultrafast pulse in the strong field limit. By analyzing the population distribution of vibrational states in the ground electronic state, we observe that chirped pulses can effectively control the resonance Raman scattering (RRS) phenomenon induced in strong fields, thereby selectively affecting the dissociation probability and branching ratio based on initial vibrational states. Furthermore, we demonstrate that by selecting an appropriate initial vibration state and controlling both the value and sign of the chirp rate, it is possible to achieve preferential cleavage of Cl+CH₂Br bonds. This study provides new insights into understanding of ultrafast coherent control of photodissociation reactions in polyatomic molecules.