Abstract: An investigation into the selection method of welding groove shapes during hybrid laser arc welding for marine medium-thick plates is presented. Testing with 20mm thickness EH36 grade steel plate,comparing the formation differences of hybrid laser arc welds in Y-shape, and U-shape with root face, and comp ound groove with root face. Moreover, comparing the forming differences of hybrid laser arc welds with varying root face and groove angle. An analysis of the influence of different grooves on the forming of hybrid laser arc welds, and the ease of preparing grooves, and the number of welding layers is also conducted. The findings indicate that acceptable forming can be achieved by employing Y-shape, and U-shape with root face, and compound grooves with root face. Taking into account the ease of groove preparation and the number of welding layers of different gro ove form, an optimal Y-shape groove is derived. It is observed that when root face value remains constant, an increa se in groove angle to a certain extent is benefit to top formation of hybrid laser arc welds. When groove angle value remains constant, a reduction in root edge to a certain extent is benefit to back formation of hybrid laser arc welds.