Johnnetta B. Cole, one of the nation's most charismatic black educators who over the past decade has gained national attention for her academic and fund-raising success at Spelman College here, announced today that she would resign as president of the college at the end of the academic year next June.

Dr. Cole, who recently presided over a fund-raising campaign that raised $114 million, the largest amount ever raised for a historically black college or university, said she wanted to take a year off to write and think before returning to Atlanta to teach at Emory University.

''There has been no pressure whatsoever for me to leave Spelman,'' she told students today at the college, which was founded in 1881 as Atlanta Baptist Seminary and is now a highly selective college for 2,000 women. ''While it is not the case that I must go, it is the right time for me to go.''

Dr. Cole said that when she came to Spelman in 1987 as its first African-American female president, she expected to stay about 10 years, and that the average career span of a college president was seven years.