Abstract: The endangered species Adenophora lobophylla population distributes in the northwest area of Sichuan province Jinchuan county,the all area is estimated not more than 500 km².According to evidence of the literature and spacemen collected in 1950's,the distribution of A.lobophylla population is reducing.In the normal condition,the reproduction of A.lobophylla ppopulation is mainly sexual.However,when suffered the external serious disturbance and drought in the spring,it could make asexual reproduction.The distribution area below altitude 2700m A.lobophylla population performs scatter distributive pattern,not good at growth and development, and declining tendancy of population.In the better condition,at altitude 2700-2900m the A.lobophylla population performs normal growth and development,higher yield of flower and fruit and reasonable age structure.Above the altitude 3000m,the number of stemtiller,flower and fruit is decreased,and the life span is shortened.The communities including A.lobophylla populations could be classed to be Populus davidiana Dode forest;xerophilous thorny brushwood or brushland;xerophilous brush grassland and xerophilous thick growth of grass.A.lobophylla populations live in these communities and are influenced by many external factors.

Key words: Engangered plant, A.denophora lobophylla, Biological and ecological characteristics, Northwest of Sichuan Province