A crawler-type travelling chassis comprises a travelling crane frame (1), crawler assemblies (2), support leg components (4) and support leg swing cylinders (5), wherein the crawler assemblies (2) are parallelly arranged on two sides of the travelling crane frame (1), the support leg components (4) are combined with the crawler assemblies (2), and the support leg swing cylinders (5) are used for driving the support leg components (4) to swing around a hinged shaft. The crawler-type travelling chassis is characterized in that a guide beam (6) is symmetrically arranged on the travelling crane frame (1) and comprises two beams (61 and 62), the two beams are mutually nested together and horizontally extend towards the left side and the right side, the crawler assemblies (2) parallelly arranged on the two sides of the travelling crane frame (1) are respectively combined with two ends of the guide beam (6) horizontally extending towards the left side and the right side by respectively matching a shaft and a hole, chassis telescopic cylinders (3) are arranged among the travelling crane frame (1) and the crawler assemblies (2) and used for driving the crawler assemblies to longitudinally displace and move along the guide beam, and the support leg components (4) are bilaterally symmetrically arranged on the outer side surfaces of the crawler assemblies (2).