The present study provides preliminary information on floristic composition of lowland deciduous forest fragments in Thammasat University, Lampang Campus, Lampang Province, Northern Thailand. A total of 110 vascular plant species belonging to 43 families and 89 genera were collected and identified. The most common species were Dipterocarpus obtusifolius, Dipterocarpus tuberculatus, Cratoxylum cochinchinense, Diospyros ehretioides, Garcinia nigrolineata, and Anacardium occidentale. The structural profiles of straight stems, sparsely distributed trees, and open crowns with 3 layers were constructed. In addition, the lowland deciduous forest fragments on the campus are considered the young to the intermediate-staged secondary forests in the present study.