1. set theory: the basic concepts and definitions in probability theory are based on set theory. Understanding the basic concepts such as set, element, subset, empty set and complete set is the basis of learning probability theory.

2. Algebra: Some calculation and derivation processes in probability theory involve algebraic operations, such as addition, multiplication, exponent, logarithm, etc. Mastering these basic algebraic operations is very important for understanding and applying the concepts and methods of probability theory.

3. Calculus: Some concepts and methods in probability theory are closely related to calculus, such as expected value, variance and cumulative distribution function. Understanding the basic concepts and operation rules of calculus such as limit, derivative and integral is very important for understanding and applying the formulas and theorems of probability theory.

4. Statistics: Probability theory is the basis of statistics, and some basic concepts and methods of statistics are also helpful to understand and apply probability theory. Understanding the methods of data collection, sorting, description and analysis, such as frequency distribution table, histogram, sample mean and standard deviation, is very helpful to understand the application of probability theory.

5. permutation and combination: some calculation and derivation processes in probability theory involve the concepts and methods of permutation and combination, such as permutation, combination and binomial coefficient. Mastering the basic knowledge of these permutations and combinations is very important for understanding and applying the probability calculation and combination problems in probability theory.

In short, learning probability theory requires some basic knowledge of set theory, algebra, calculus, statistics, permutation and combination. These basic knowledge provide a necessary foundation for understanding and applying the concepts and methods of probability theory, and also lay a solid foundation for further study and application of probability theory.