Three Structure Diagrams
Before writing requirements, draw three tree diagrams: functional structure, information structure, product structure. The order can't be reversed, and mashing them into one makes no sense to anyone.
- 画了一张大图，功能和字段全塞在上面，最后自己都看不懂
- 跟开发讨论时对不上，因为图上没有对象和字段
- 直接开始画原型，画到一半推翻重来，陷在细节里出不来
What each diagram is for
| 图 | 回答什么 | 画什么 | 主要用途 |
|---|---|---|---|
| 功能结构图 | 产品有哪些功能模块，怎么划分 | 树状，功能名，2~3 级 | 梳理需求范围，对齐设计思路 |
| 信息结构图 | 每个业务对象包含哪些信息 | 以对象为根，字段为枝 | 给开发做数据表设计参考 |
| 产品结构图 | 功能和信息怎么落到页面上 | 页面框架 + 各页承载的信息 | 替代原型做评审，指导画原型 |
How to draw each one
The most common mistake with the information structure diagram is listing information page by page. It should step back and survey the whole information system by object—the same user object's information appears on many pages, but it's drawn only once on the diagram.
How it differs from architecture and flow diagrams
| 类型 | 描述什么 | 形式 | 什么时候用 |
|---|---|---|---|
| 结构图 | 系统由哪些部分组成，静态的组成关系 | 框图、树状图 | 写需求文档之前，梳理业务 |
| 架构图 | 组件之间怎么交互、依赖，信息怎么流动 | 框图 | 系统设计、软件与网络架构 |
| 流程图 | 步骤的顺序和条件分支 | 流程符号、泳道图 | 用户操作流程、业务流程分析 |
How many to draw if you're solo
Drawing all three is the safest, but a solo PM can choose based on project complexity.
- For a small tool: the IA diagram is enough. There are only a few features, but if you get the objects and fields wrong, everything downstream feels off.
- With multiple roles or business lines: you need all three. Feature ownership and permission boundaries have to be drawn clearly first.
- Mostly content display: feature structure plus product structure. The data model is usually simple; the focus is on how it's organized.
- If you only draw one: pick the IA diagram. It's the only one that forces a database rebuild if you get it wrong — the other two are much cheaper to change.
The form doesn't matter. A mind map, indented text, an AI-generated Mermaid snippet—all fine. Their value is in forcing you to think the relationships through, not in the deliverable itself—which is also why they can replace a prototype for review: changing a node takes seconds; revising a prototype takes half a day.