台灣是以出口為導向的經濟型態，出口貿易佔總需求30％以上，國內經濟景氣的變化與全球工業化國家經濟的榮枯關係實甚為密切，尤其是對出口比重重達24.2％的美國，23.5％的香港。而台海兩岸的經貿活動也隨著業者積極前往大陸投資更是以倍數的速度成長，大陸地區一躍成為台灣最主要的海外投資地區之一。
　　故本文藉由向量因果關係及雙變量異質變異數所求算出之條件相關係數的使用，尋找與台灣貿關係最強的美國、香港、大陸等股巿間的因果關係，以及佔台灣出口比例最重的電子業與美國高科技股之間的股價關連性：同時台灣分類電子產業上中下間是否會因產品週期及供需的影響亦有因果關係之存在，亦是本文之研究重點。
　　研究結果發現：1.台灣發行量股價指數與與美國大盤股價指數之間存在單向性的因果關係，唯其條件相關係數並不高、香港恆生股價指數與台灣股價指數間互相存有因果關係、大陸深圳A、B股價指數與上海A、B股價指數與台灣發行量股價指數間並不存在因果關係。2.美國高科技股與台灣電子股間互相存在因果關係，尤以那斯達克電子股與台灣電子股關係更是明顯。半導體產業中下游間存有因果關係、桌上型電腦產業上下游間及筆記型電腦產業上下游間存在有高度的因果關係。

　　Taiwan is a country oriented by exporting which occupies aggregate demand more than 30%.We can agree with it, the changing of domestic economic is connecte close economicof global industrial countries, especially for USA and HK.And also the investment growth rate between Taiwan and Mainland China grows with a high speed. Invest environment in Mainland China have already became one of the popular abroad investing area of Taiwan.
　　The aim of this paper is to explore the causality correlation among these equity markets shows the strong trading connection with Taiwan. And the correlation of stock index of high tech. Industrial between Taiwan and America is the second point to explore in our study. Owing to the relationship of supply and demand, the causality between upstream and downstream of the same electric industrial is also our purpose to explore by using new model and methodology of VARMA and conditional correlation..
　　The empirical result are as following:
　　(1) There exist unidirectional causality relationship between stock index of TWN and USA. However, the conditional correlation does not strong enough. There exist the feedback causality correlation between stock index of TWN and HK; and there do not exist any relationship in stock markets between TWN and M. China. (2) There exist causality relationship between stock index of high tech. Industrial in TWN and USA, especially between NASDAQ Electric Stock Index and Taiwan Electric Stock Index. (3) There have causality relationship between midstream stock index and downstream stock index in semicondusto. There also have causality relationship between upstream stock index and downstream stock index and downstream stock index in Desk-Computer industrial and Note Book industrial.