At the beginning of learning, not all students have good initial abilities. Most students need a better initial ability to participate in learning ratio problem-solving. On the other hand, if you have to prepare students to be ready to take part in learning mathematics, the teacher will experience difficulties, moreover, if the teacher has to give unequal treatment to every student before learning. Through a qualitative descriptive approach, this study aims to describe student errors in solving ratio problems in students with fairly good initial abilities. A total of 32 junior high school students in Klaten were research subjects and were given a preliminary ability test. According to the initial ability test that has been provided, it shows that more than 50% of students have a fairly good initial ability. All students with fairly good initial abilities were given a ratio problem-solving test. Based on the results of comparative problem-solving, two students were selected to be interviewed. From this analysis, it was concluded that students' errors in solving comparative problems include: understanding the problem (writing variables or problem information given), planning problem-solving (choosing problem-solving strategies, writing mileage formulas), and solving problems (substituting values into equations/formulas). , illustrating the problem into mathematical symbols), and reviewing problem-solving (writing conclusions, converting time measurement units).