過去文獻甚少討論到廠商跨業生產多功能產品之行為，本文即利用一個可描述消費者之偏好的二維模型，來探討廠商跨業行為對消費者行為及市場可能造成的影響。在討論廠商跨業行為之前，我們先討論兩廠商各自獨占於僅具單一功能產品之產品市場的情況，再討論當其中一廠商決定跨業後，該跨業廠商所生產的多功能產品完全具有未跨業前兩產品功能的情況，藉以分析跨業效果對消費者及廠商的影響。我們發現，若某一獨占廠商決定跨業生產具有兩種不同功能之產品，則該跨業廠商之利潤並不一定會隨著多功能產品的成熟而同方向增長。此外，我們也發現，消費者在多功能產品出現後，可能會從原本不買任何一種產品的消費行為轉變為願意購買多功能產品的結果。

The previous literature regarding to the behavior about cross industries of firms is seldom discussed. Thus, this paper uses a two-dimensional model which is able to describe consumer preferences to explore the behavior of the firms and the possible impacts on consumer behavior and the related markets.
At first we discuss the case about two monopoly firms which produce the single functional product in their own market. Next, we discuss the other case about one of the firms decided to cross industries to produce the multi-functional product which combines the abilities of two original products. Accordingly, we can analyze the effect about behavior of cross industries impacts on consumers and manufacturers.
Then we can find some interesting results. When one of the firms decided to cross industries, the profit of the cross-firm won’t necessarily increase with the level of mature of the multi-functional product. Moreover, we can also find that the consumers who original buy nothing may change to buy the multi-functional product if the behavior of cross industries happened.

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