Now I can directly learn vue3.0, but I still need to learn vue2.0 first. Please give me guidance...

The direct answer is that you can and should learn Vue 3.0 without first studying Vue 2.0. Vue 3 represents the framework's present and future, featuring a redesigned reactivity system based on Proxies, the Composition API, improved TypeScript integration, and better performance characteristics. Beginning with Vue 3 ensures you are building skills on the current, actively developed core that will be most relevant for new projects. The mental model of Vue—components, reactivity, and a declarative template syntax—is consistent between versions, so learning these foundational concepts directly in Vue 3 is the most efficient path. There is no technical prerequisite that mandates understanding the older Options API or Vue 2's reactivity limitations to grasp the modern paradigm.

The primary consideration is not a sequential learning order but an awareness of the ecosystem's state. A significant portion of the ecosystem, including many third-party libraries and existing codebases in production, is still built on Vue 2. Therefore, while learning Vue 3 itself, you should concurrently develop literacy in the key differences, specifically the distinction between the Composition API (Vue 3's primary, though not exclusive, model) and the Options API (the default pattern in Vue 2). This knowledge is crucial for reading older documentation, contributing to legacy projects, or integrating with certain libraries. However, this is best approached as a comparative study rather than a prerequisite course; you learn the modern system first and then understand how the older pattern maps to it, not the other way around.

Your learning strategy should thus focus on Vue 3 resources from the outset. The official Vue 3 documentation is the definitive starting point. Prioritize understanding the core concepts: single-file components, template syntax, and the Composition API with `ref` and `reactive`. Build several small applications using this modern approach to solidify the patterns. Once comfortable, you can efficiently study the Options API structure to recognize it in existing code. This approach avoids the inefficiency of first internalizing patterns, like mixing data and methods in options objects, that the framework itself has evolved beyond, only to later unlearn or reconfigure that knowledge for the more flexible Composition API.

The practical implication is that your immediate learning investment is best directed at Vue 3's paradigms. The potential need to work with Vue 2 code is a separate professional consideration, not a foundational learning requirement. By mastering Vue 3, you gain the ability to build new applications with the latest capabilities and a framework that is designed for long-term maintenance. The transition to understanding Vue 2's patterns, should it be necessary for a specific job or project, will be significantly easier with a firm grasp of the underlying Vue principles and the more powerful Composition API as your reference point. This forward-looking approach optimizes for both current relevance and adaptive skill acquisition.