Quantum Fisher Information plays a central role in the fields of quantum metrology and quantum precision measurement. However, quantum systems are susceptible to the influence of noisy environments, which reduces the precision of parameter estimation (as measured by quantum Fisher information). Therefore, overcoming the impact of environmental noise on quantum systems to enhance the quantum Fisher information of parameters has become an important scientific issue in quantum precision measurement. In this paper, we investigate the enhancement of phase estimation precision for a two-level atom subjected to a zero-temperature bosonic environment, based on a continuous null-result measurement scheme. First, an analytical expression for the final state of the atomic system after n null-result measurements is derived. To highlight the crucial role of continuous measurement in the dynamics of the two-level atom, the core amplitude coefficient in the final state is reformulated into a specific form, yielding a concise mathematical expression. Interestingly, we find that the dynamics of the two-level atom under continuous measurements are closely related to a scaling parameter—the product of the environmental spectral width and the measurement time interval. In certain special cases, this formulation reduces to known results such as the quantum Zeno effect and Markovian approximations. Furthermore, we demonstrate that, under both Markovian and non-Markovian conditions, the quantum Fisher information for the atomic phase estimation can be significantly enhanced by tuning this scaling parameter. Using an exactly solvable model, we also provide an explanation for the quantum Zeno effect without explicit use of the projection postulate, and find that in certain limits, a concise formula for $\tilde{h}(t) = h^n(\tau)$ accurately captures the numerical results across a broad range of parameters. In summary, the proposed scheme of frequent null-result measurements with post-selection on the environment effectively mitigates the detrimental effects of decoherence on the quantum Fisher information, offering a novel theoretical approach for achieving high-precision measurements in open quantum systems.