BANGKOK, Thailand (AP) _ Do Muoi's organizational skills and discipline won him Vietnam's premiership three years ago, but it apparently was his pragmatic economic views that earned him the post of Communist Party general secretary.

Do Muoi, 74, played a key role in implementing the Western-style economic reforms that the man he is replacing, Nguyen Van Linh, pursued after becoming party chief at the sixth national party congress in late 1986.

Do Muoi has been premier since 1988, replacing Pham Hung, who died.

A Western diplomat in Bangkok characterized Do Muoi as ''a conservative guy who has become a supporter of reform. He has educated himself tremendously in economics.''

When Foreign Minister Taro Nakayama of Japan visited Hanoi in June, Do Muoi told him that he wanted to learn how Japan became an economic success after much of its industry was ruined in World War II, a Japanese diplomat said.

The diplomats spoke on condition of anonymity.

For most of his career, Do Muoi was a virtual unknown among Vietnamese citizens.

A Vietnamese Foreign Ministry official has said that he had never even seen Do Muoi before he became prime minister.

''He doesn't have much of a public image - the public knows virtually nothing about him,'' said the official said, also speaking on condition of anonymity.

The official said the party picked Do Muoi for the top government post in 1988 ''because he has the reputation for discipline and toughness, and the party needs greater organization and control.''

Do Muoi had been the No. 2 man in the party secretariat, where he dealt with the day-to-day affairs of the party organization and implementing policies.

His official biography says Do Muoi was born Feb. 2, 1917, in Dong My village on the outskirts of Hanoi. His family members were peasants and he initially became a painter.

He joined the budding nationalist movement in 1936 while still a teen-ager and the Indochinese Communist Party three years later.

Do Muoi was arrested in 1941 and sentenced to 10 years in prison for his anti-French activities. But he escaped from Hanoi's Hoa Lo Prison in 1945 and rejoined the party.

In 1946 he was made secretary of the party committee in what now is Ha Nam Ninh province in the north.

In March 1955 he became an alternate member of the party Central Committee. A year later he was made vice minister of home trade, and took over that ministry in 1958.

He was elected a full member of the Central Committee in 1960.

In 1967 he was appointed head of the State Pricing Commission, and in 1969 became vice premier. In 1973 he also became minister of construction.

Do Muoi was elected an alternate member of the ruling Politburo of unified Vietnam in 1976. During his seven years as vice premier, starting in 1981, Do Muoi was responsible for economic management and foreign economic relations.

He was elected a full member of the Politburo in 1982.