The objective of this study was to survey and explore physical evidence and problems of trees along the PEA electricity transmission line : A case study of the electricity transmission line on highway 1001, Sansai, Chiang Mai. The study site cover 4 municipalities namely : Maejo, Nongharn, Jedeemaekrue, and Maefag. Premary data was collected by choosing a type of the areas having the lowest score of the assessment (first two areas) in each municipality based on commutation traits and the standard criteria used for the assessment of species. Findings show that there are 93 trees from 13 families which Lythraceae, Verbenaceae, and Caesalpiniaceae are found most, respectively. Besides, it scatters almost all of the municipalities. Based on GPS presentation of the scope of this study, there are trees with a middle size of about 10-25 meters in height and large size of more than 25 meters in high, and has a bush shape during the second and third of growth period. Based on the bush shape, circle and oval shapes are found most and followed by wide-oval shape. Most of the trees are soft woody and deciduous. The flower are yellow or pink, and not fragrant. Its flowering period is not throughout the year which may have on effect on the aesthetic continuity of the edges of the roads. Regarding a survey on the trees deterioration, there is not a clear guideline for maintenance particularly on pruning and scar repairing. This terioration has an effect on clearly abnormal of the trees. That is, the width volume of its branches is lessen to 44.75%. Branch and Trunk damages can be observed clearly up to 37.5%. All of these data are analyzed to support the presentation of standard practice principles in the maintenance of trees along the electricity transmission line.