Thermal conductivity of a material is one of the important parameters of its thermal properties and efficiency in measuring the thermal conductivity of a material is of great significance in an engineering sense. In the engineering field, quite a number of materials are transversely isotropic. A common method to measure the thermal conductivities of transversely isotropic materials is the guarded hot-plate (GHP) method, which applies heat flux to the specimen respectively in different directions inducing steady-state temperature field in the material and obtains the conductivity of each direction via the relationship between the heat flux and the temperature gradient. This method as a steady-state method is theoretically simple but time-consuming, limited to those scenarios where there are many specimens to be tested. Transient line heat source (LHS) method, based on the transient heat conduction theory, is a simple and effective method in measuring thermal conductivities of materials. The function of LHS method was extended based on the heat conduction theory in transversely isotropic media. A new method of measuring thermal conductivities of transversely isotropic materials with LHS method was proposed. The newly proposed method was validated by comparing with guarded hot-plate method based on the results from a test on specimens made of an artificial transversely isotropic material. It turns out that reliable and reproducible results can be obtained as long as the actual needle-specimen system under each single measurement is close enough to its corresponding idealized model.