He published the works comprehensively dealing with the idea and theory on the revolutionary outlook on leader, which had arisen as an urgent question in the development of the revolutionary theory of the working class.

He authored such works as "The Leader of the Working Class Plays the Decisive Role in the Revolutionary Struggle" and "Our Leader Is the Great Statesman" are of great theoretical and practical significance in formulating the idea and theory on the revolutionary outlook on leader and realizing the ideological and volitional unity and cohesion of all Party members on the basis of the idea of the President.

He authored works dealing with the unique military idea of the President and some matters in the study of his military idea, thus clarifying the originality of the military idea and army-building theory of the President, the main features and advantages of the Juche-based war method and principled matters in embodying them.

In his works "On Correctly Understanding the Validity of the Basic Line of Socialist Economic Construction" and "Let Us Staunchly Champion Our Party's Line of Building an Independent National Economy", Kim Jong Il proved the validity and uniqueness of the WPK's line and policy on the socialist economic construction and indicated tasks facing various sectors of the national economy to carry them out.

In his graduation thesis "The Status and Role of the County in Socialist Construction" he defended, preserved and developed the idea and theory on regional base in socialist construction advanced by the President in his work "Theses on the Socialist Rural Question in Our Country."

There are also works indicating the tasks and ways to conduct the socialist cultural construction in a revolutionary manner.

They are of epochal significance in establishing the Juche-oriented outlook on history.

His works also scientifically analyzed the characteristics of modern imperialism and the inevitability of its destruction, consolidated the ideological and theoretical basis of the strategy in the struggle against imperialists. They also shed light on the true colors of modern revisionism embellishing imperialism.