Abstract: Accurate determination of phosphorus (P) content in geological samples is a crucial prerequisite for in-depth investigations into the geochemical behavior, biological effects, and ore forming mechanisms of P. Phosphorus contents in geological samples vary widely; except for phosphorus-rich samples such as phosphate ores, most geological samples exhibit low to medium P concentrations (1–1000 µg/g), and their complex matrix compositions pose significant challenges to precise quantification of P. This paper systematically reviews the analytical techniques for P in geological samples, covering major sample preparation methods and instrumental analyses, and evaluates the characteristics and applicability of these techniques. Sample preparation includes acid digestion, alkaline fusion, and fused pelletization, and measurement techniques include chemical analysis (gravimetry, volumetry) and instrumental analysis such as spectrophotometry, inductively coupled plasma-optical emission spectrometry (ICP-OES), X-ray fluorescence spectrometry (XRF), inductively coupled plasma-mass spectrometry (ICP-MS), etc.. Sample preparation must be compatible with the properties of sample matrices and subsequent analytical techniques, and the selection of these preparation procedures directly affects the precision and accuracy of the results. The instrumental analyses generally provide prominent advantages such as low P detection limits (typically at the µg/g level), rapid analysis throughput, and simultaneous determination of multi-element. However, these techniques are also susceptible to various spectral interferences (e.g., matrix effects and instrument fluctuations). These obstacles can be overcome by optimizing approaches such as matrix-matched standards and internal standard calibration. Existing national and industrial standards for P analysis in geological samples have several limitations, including relatively high limits of detection (typically at the 0.01% level), cumbersome analytical workflows, outdated technical approaches, and insufficient coverage of sample types. By analyzing the characteristics of different sample preparation and analytical methods and integrating them with sample properties and analytical requirements, this paper proposes optimized analytical protocols, offering a scientific basis and practical guidance for the efficient and accurate determination of P in geological samples.