This paper introduces the role of atomic vapor cells in thermal-atom precision measurement systems, elucidates the main physical mechanisms of atomic spin relaxation and their effects on polarization lifetime, coherence time, system noise, and long-term drift. It compares the process characteristics, application scenarios, and development trends of traditional glass-fabricated vapor cells and MEMS microfabricated vapor cells, and analyzes the influence of material selection, structural design, wall-surface treatment, buffer-gas metering, and thermal–magnetic environment management on vapor-cell performance. It is proposed that an engineering-oriented framework for vapor-cell characterization and evaluation should be established, focusing on intrinsic parameters such as atomic number density, spin polarization, and relaxation time, while conducting targeted screening in combination with the system-level performance requirements of three representative applications: A—spin-exchange relaxation-free magnetometers (SERF) / optically pumped magnetometers (OPM), B—coherent population trapping atomic clocks (CPT) / chip-scale atomic clocks (CSAC), and C—nuclear magnetic resonance gyroscopes (NMRG) / comagnetometers. The paper further proposes shifting the control of key error sources upstream to the stages of vapor-cell design, fabrication, and evaluation. By establishing physical correlations between manufacturing parameters and device performance, atomic vapor cells can be advanced toward standardized devices with reproducible performance, predictable lifetime, and suitability for scalable production.