The azimuth angle of geomagnetic observatory markers is crucial for ensuring the reliability of geomagnetic observation data, and its remeasurement constitutes a core task in observatory operations. By comparing the precision, efficiency, and environmental adaptability of astronomical observation methods and GNSS differential positioning techniques for azimuth measurement, this study reveals that traditional astronomical methods suffer from significant environmental constraints and low efficiency compared to GNSS differential positioning technology. After systematically investigating the multi scenarios in azimuth remeasurement at geomagnetic observatories, five remeasurement scenarios based on GNSS differential positioning technology are proposed, addressing practical conditions such as unobstructed paths, restricted pathways, and single point deployments. Through field validations at the Hongshan, Quanzhou, and Yulin observatories, the feasibility of Scenario Ⅰ (dual GNSS deployment on unobstructed paths) and Scenario Ⅱ (multi path angles conversion) is confirmed. Field validations at Hongshan, Quanzhou, and Yulin observatories confirmed the feasibility of Scenario I (dual-GNSS deployment on unobstructed paths) and Scenario II (angular conversion across paths). Furthermore, a preliminary analysis was conducted on potential error sources in different scenarios, and a prioritized implementation sequence was established for stations that simultaneously meet the conditions of each retest scenario. This work provides a scalable technical solution for azimuth measurement in complex geomagnetic observatories environments.