This research aims to 1) study the quality of life (QOL) level development according to characteristics of Thai elderly demography 2) study the different levels of Thai elderly QOL and 3) study the relationship between QOL development and Thai elderly QOL in Nakhon Pathom province. Mixed methods research was used in this study. The sample consisted of 400 Thai elderly by using questionnaires and statistics used. The data analyzed were frequency, percentage, mean, standard deviation. The statistical t-test, one-way ANOVA analysis, and Pearson's Correlation Coefficient were determined. Found that 1) the QOL improvement, the overall picture is at a high level, social support had the highest average, followed by environmental management, participation and health promotion 2) the elderly QOL, the environment was at a high level, followed by social, psychological, and physical relationships 3) overall QOL improvement was positively related to the elderly QOL according to the statistical significance assumptions at the level. 01 and 4) from the municipal administrators of Nakhon Pathom province interviewing, found that the QOL improvement in various areas municipality affecting the elderly QOL when the elderly are developed, they will have a better QOL.