An improved tree-ring dating method able to detect and count tree-ring boundaries from images of wood cross sections is introduced. It can also be developed to analyze tree-ring features in future research. This proposed method first uses hue saturation intensity (HSI) color to get rid of the blue background to obtain the region of interest, the wood section. Then, using the watershed method and the window method, sapwood and heartwood regions are segmented, and the segmented image is dichotomized by the method, followed by cross calibrated miss detection correction to add missed rings. In order to reduce the fallout ratio, a method based on distance limitations is also utilized. In this way, the total number of the tree-rings are finally counted. A pilot study was conducted using seven images from an online library and five scanned images of Pinus massoniana wood discs provided by Zhejiang A&F University. Experimental results show that this method can be used to count ring numbers even when the color difference of sapwood and heartwood is distinct, and is able to correct the miss and fallout detection errors, increasing the accuracy of tree-ring dating.